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| author | cyfraeviolae <cyfraeviolae> | 2024-04-03 03:10:44 -0400 |
|---|---|---|
| committer | cyfraeviolae <cyfraeviolae> | 2024-04-03 03:10:44 -0400 |
| commit | 6d7ba58f880be618ade07f8ea080fe8c4bf8a896 (patch) | |
| tree | b1c931051ffcebd2bd9d61d98d6233ffa289bbce /venv/lib/python3.11/site-packages/sqlalchemy/sql/schema.py | |
| parent | 4f884c9abc32990b4061a1bb6997b4b37e58ea0b (diff) | |
venv
Diffstat (limited to 'venv/lib/python3.11/site-packages/sqlalchemy/sql/schema.py')
| -rw-r--r-- | venv/lib/python3.11/site-packages/sqlalchemy/sql/schema.py | 6115 |
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diff --git a/venv/lib/python3.11/site-packages/sqlalchemy/sql/schema.py b/venv/lib/python3.11/site-packages/sqlalchemy/sql/schema.py new file mode 100644 index 0000000..6d5f941 --- /dev/null +++ b/venv/lib/python3.11/site-packages/sqlalchemy/sql/schema.py @@ -0,0 +1,6115 @@ +# sql/schema.py +# Copyright (C) 2005-2024 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""The schema module provides the building blocks for database metadata. + +Each element within this module describes a database entity which can be +created and dropped, or is otherwise part of such an entity. Examples include +tables, columns, sequences, and indexes. + +All entities are subclasses of :class:`~sqlalchemy.schema.SchemaItem`, and as +defined in this module they are intended to be agnostic of any vendor-specific +constructs. + +A collection of entities are grouped into a unit called +:class:`~sqlalchemy.schema.MetaData`. MetaData serves as a logical grouping of +schema elements, and can also be associated with an actual database connection +such that operations involving the contained elements can contact the database +as needed. + +Two of the elements here also build upon their "syntactic" counterparts, which +are defined in :class:`~sqlalchemy.sql.expression.`, specifically +:class:`~sqlalchemy.schema.Table` and :class:`~sqlalchemy.schema.Column`. +Since these objects are part of the SQL expression language, they are usable +as components in SQL expressions. + +""" +from __future__ import annotations + +from abc import ABC +import collections +from enum import Enum +import operator +import typing +from typing import Any +from typing import Callable +from typing import cast +from typing import Collection +from typing import Dict +from typing import Iterable +from typing import Iterator +from typing import List +from typing import Mapping +from typing import NoReturn +from typing import Optional +from typing import overload +from typing import Sequence as _typing_Sequence +from typing import Set +from typing import Tuple +from typing import TYPE_CHECKING +from typing import TypeVar +from typing import Union + +from . import coercions +from . import ddl +from . import roles +from . import type_api +from . import visitors +from .base import _DefaultDescriptionTuple +from .base import _NoneName +from .base import _SentinelColumnCharacterization +from .base import _SentinelDefaultCharacterization +from .base import DedupeColumnCollection +from .base import DialectKWArgs +from .base import Executable +from .base import SchemaEventTarget as SchemaEventTarget +from .coercions import _document_text_coercion +from .elements import ClauseElement +from .elements import ColumnClause +from .elements import ColumnElement +from .elements import quoted_name +from .elements import TextClause +from .selectable import TableClause +from .type_api import to_instance +from .visitors import ExternallyTraversible +from .visitors import InternalTraversal +from .. import event +from .. import exc +from .. import inspection +from .. import util +from ..util import HasMemoized +from ..util.typing import Final +from ..util.typing import Literal +from ..util.typing import Protocol +from ..util.typing import Self +from ..util.typing import TypedDict +from ..util.typing import TypeGuard + +if typing.TYPE_CHECKING: + from ._typing import _AutoIncrementType + from ._typing import _DDLColumnArgument + from ._typing import _InfoType + from ._typing import _TextCoercedExpressionArgument + from ._typing import _TypeEngineArgument + from .base import ReadOnlyColumnCollection + from .compiler import DDLCompiler + from .elements import BindParameter + from .functions import Function + from .type_api import TypeEngine + from .visitors import _TraverseInternalsType + from .visitors import anon_map + from ..engine import Connection + from ..engine import Engine + from ..engine.interfaces import _CoreMultiExecuteParams + from ..engine.interfaces import CoreExecuteOptionsParameter + from ..engine.interfaces import ExecutionContext + from ..engine.mock import MockConnection + from ..engine.reflection import _ReflectionInfo + from ..sql.selectable import FromClause + +_T = TypeVar("_T", bound="Any") +_SI = TypeVar("_SI", bound="SchemaItem") +_TAB = TypeVar("_TAB", bound="Table") + + +_CreateDropBind = Union["Engine", "Connection", "MockConnection"] + +_ConstraintNameArgument = Optional[Union[str, _NoneName]] + +_ServerDefaultArgument = Union[ + "FetchedValue", str, TextClause, ColumnElement[Any] +] + + +class SchemaConst(Enum): + RETAIN_SCHEMA = 1 + """Symbol indicating that a :class:`_schema.Table`, :class:`.Sequence` + or in some cases a :class:`_schema.ForeignKey` object, in situations + where the object is being copied for a :meth:`.Table.to_metadata` + operation, should retain the schema name that it already has. + + """ + + BLANK_SCHEMA = 2 + """Symbol indicating that a :class:`_schema.Table` or :class:`.Sequence` + should have 'None' for its schema, even if the parent + :class:`_schema.MetaData` has specified a schema. + + .. seealso:: + + :paramref:`_schema.MetaData.schema` + + :paramref:`_schema.Table.schema` + + :paramref:`.Sequence.schema` + + """ + + NULL_UNSPECIFIED = 3 + """Symbol indicating the "nullable" keyword was not passed to a Column. + + This is used to distinguish between the use case of passing + ``nullable=None`` to a :class:`.Column`, which has special meaning + on some backends such as SQL Server. + + """ + + +RETAIN_SCHEMA: Final[Literal[SchemaConst.RETAIN_SCHEMA]] = ( + SchemaConst.RETAIN_SCHEMA +) +BLANK_SCHEMA: Final[Literal[SchemaConst.BLANK_SCHEMA]] = ( + SchemaConst.BLANK_SCHEMA +) +NULL_UNSPECIFIED: Final[Literal[SchemaConst.NULL_UNSPECIFIED]] = ( + SchemaConst.NULL_UNSPECIFIED +) + + +def _get_table_key(name: str, schema: Optional[str]) -> str: + if schema is None: + return name + else: + return schema + "." + name + + +# this should really be in sql/util.py but we'd have to +# break an import cycle +def _copy_expression( + expression: ColumnElement[Any], + source_table: Optional[Table], + target_table: Optional[Table], +) -> ColumnElement[Any]: + if source_table is None or target_table is None: + return expression + + fixed_source_table = source_table + fixed_target_table = target_table + + def replace( + element: ExternallyTraversible, **kw: Any + ) -> Optional[ExternallyTraversible]: + if ( + isinstance(element, Column) + and element.table is fixed_source_table + and element.key in fixed_source_table.c + ): + return fixed_target_table.c[element.key] + else: + return None + + return cast( + ColumnElement[Any], + visitors.replacement_traverse(expression, {}, replace), + ) + + +@inspection._self_inspects +class SchemaItem(SchemaEventTarget, visitors.Visitable): + """Base class for items that define a database schema.""" + + __visit_name__ = "schema_item" + + create_drop_stringify_dialect = "default" + + def _init_items(self, *args: SchemaItem, **kw: Any) -> None: + """Initialize the list of child items for this SchemaItem.""" + for item in args: + if item is not None: + try: + spwd = item._set_parent_with_dispatch + except AttributeError as err: + raise exc.ArgumentError( + "'SchemaItem' object, such as a 'Column' or a " + f"'Constraint' expected, got {item!r}" + ) from err + else: + spwd(self, **kw) + + def __repr__(self) -> str: + return util.generic_repr(self, omit_kwarg=["info"]) + + @util.memoized_property + def info(self) -> _InfoType: + """Info dictionary associated with the object, allowing user-defined + data to be associated with this :class:`.SchemaItem`. + + The dictionary is automatically generated when first accessed. + It can also be specified in the constructor of some objects, + such as :class:`_schema.Table` and :class:`_schema.Column`. + + """ + return {} + + def _schema_item_copy(self, schema_item: _SI) -> _SI: + if "info" in self.__dict__: + schema_item.info = self.info.copy() + schema_item.dispatch._update(self.dispatch) + return schema_item + + _use_schema_map = True + + +class HasConditionalDDL: + """define a class that includes the :meth:`.HasConditionalDDL.ddl_if` + method, allowing for conditional rendering of DDL. + + Currently applies to constraints and indexes. + + .. versionadded:: 2.0 + + + """ + + _ddl_if: Optional[ddl.DDLIf] = None + + def ddl_if( + self, + dialect: Optional[str] = None, + callable_: Optional[ddl.DDLIfCallable] = None, + state: Optional[Any] = None, + ) -> Self: + r"""apply a conditional DDL rule to this schema item. + + These rules work in a similar manner to the + :meth:`.ExecutableDDLElement.execute_if` callable, with the added + feature that the criteria may be checked within the DDL compilation + phase for a construct such as :class:`.CreateTable`. + :meth:`.HasConditionalDDL.ddl_if` currently applies towards the + :class:`.Index` construct as well as all :class:`.Constraint` + constructs. + + :param dialect: string name of a dialect, or a tuple of string names + to indicate multiple dialect types. + + :param callable\_: a callable that is constructed using the same form + as that described in + :paramref:`.ExecutableDDLElement.execute_if.callable_`. + + :param state: any arbitrary object that will be passed to the + callable, if present. + + .. versionadded:: 2.0 + + .. seealso:: + + :ref:`schema_ddl_ddl_if` - background and usage examples + + + """ + self._ddl_if = ddl.DDLIf(dialect, callable_, state) + return self + + +class HasSchemaAttr(SchemaItem): + """schema item that includes a top-level schema name""" + + schema: Optional[str] + + +class Table( + DialectKWArgs, HasSchemaAttr, TableClause, inspection.Inspectable["Table"] +): + r"""Represent a table in a database. + + e.g.:: + + mytable = Table( + "mytable", metadata, + Column('mytable_id', Integer, primary_key=True), + Column('value', String(50)) + ) + + The :class:`_schema.Table` + object constructs a unique instance of itself based + on its name and optional schema name within the given + :class:`_schema.MetaData` object. Calling the :class:`_schema.Table` + constructor with the same name and same :class:`_schema.MetaData` argument + a second time will return the *same* :class:`_schema.Table` + object - in this way + the :class:`_schema.Table` constructor acts as a registry function. + + .. seealso:: + + :ref:`metadata_describing` - Introduction to database metadata + + """ + + __visit_name__ = "table" + + if TYPE_CHECKING: + + @util.ro_non_memoized_property + def primary_key(self) -> PrimaryKeyConstraint: ... + + @util.ro_non_memoized_property + def foreign_keys(self) -> Set[ForeignKey]: ... + + _columns: DedupeColumnCollection[Column[Any]] + + _sentinel_column: Optional[Column[Any]] + + constraints: Set[Constraint] + """A collection of all :class:`_schema.Constraint` objects associated with + this :class:`_schema.Table`. + + Includes :class:`_schema.PrimaryKeyConstraint`, + :class:`_schema.ForeignKeyConstraint`, :class:`_schema.UniqueConstraint`, + :class:`_schema.CheckConstraint`. A separate collection + :attr:`_schema.Table.foreign_key_constraints` refers to the collection + of all :class:`_schema.ForeignKeyConstraint` objects, and the + :attr:`_schema.Table.primary_key` attribute refers to the single + :class:`_schema.PrimaryKeyConstraint` associated with the + :class:`_schema.Table`. + + .. seealso:: + + :attr:`_schema.Table.constraints` + + :attr:`_schema.Table.primary_key` + + :attr:`_schema.Table.foreign_key_constraints` + + :attr:`_schema.Table.indexes` + + :class:`_reflection.Inspector` + + + """ + + indexes: Set[Index] + """A collection of all :class:`_schema.Index` objects associated with this + :class:`_schema.Table`. + + .. seealso:: + + :meth:`_reflection.Inspector.get_indexes` + + """ + + _traverse_internals: _TraverseInternalsType = ( + TableClause._traverse_internals + + [("schema", InternalTraversal.dp_string)] + ) + + if TYPE_CHECKING: + + @util.ro_non_memoized_property + def columns(self) -> ReadOnlyColumnCollection[str, Column[Any]]: ... + + @util.ro_non_memoized_property + def exported_columns( + self, + ) -> ReadOnlyColumnCollection[str, Column[Any]]: ... + + @util.ro_non_memoized_property + def c(self) -> ReadOnlyColumnCollection[str, Column[Any]]: ... + + def _gen_cache_key( + self, anon_map: anon_map, bindparams: List[BindParameter[Any]] + ) -> Tuple[Any, ...]: + if self._annotations: + return (self,) + self._annotations_cache_key + else: + return (self,) + + if not typing.TYPE_CHECKING: + # typing tools seem to be inconsistent in how they handle + # __new__, so suggest this pattern for classes that use + # __new__. apply typing to the __init__ method normally + @util.deprecated_params( + mustexist=( + "1.4", + "Deprecated alias of :paramref:`_schema.Table.must_exist`", + ), + ) + def __new__(cls, *args: Any, **kw: Any) -> Any: + return cls._new(*args, **kw) + + @classmethod + def _new(cls, *args: Any, **kw: Any) -> Any: + if not args and not kw: + # python3k pickle seems to call this + return object.__new__(cls) + + try: + name, metadata, args = args[0], args[1], args[2:] + except IndexError: + raise TypeError( + "Table() takes at least two positional-only " + "arguments 'name' and 'metadata'" + ) + + schema = kw.get("schema", None) + if schema is None: + schema = metadata.schema + elif schema is BLANK_SCHEMA: + schema = None + keep_existing = kw.get("keep_existing", False) + extend_existing = kw.get("extend_existing", False) + + if keep_existing and extend_existing: + msg = "keep_existing and extend_existing are mutually exclusive." + raise exc.ArgumentError(msg) + + must_exist = kw.pop("must_exist", kw.pop("mustexist", False)) + key = _get_table_key(name, schema) + if key in metadata.tables: + if not keep_existing and not extend_existing and bool(args): + raise exc.InvalidRequestError( + f"Table '{key}' is already defined for this MetaData " + "instance. Specify 'extend_existing=True' " + "to redefine " + "options and columns on an " + "existing Table object." + ) + table = metadata.tables[key] + if extend_existing: + table._init_existing(*args, **kw) + return table + else: + if must_exist: + raise exc.InvalidRequestError(f"Table '{key}' not defined") + table = object.__new__(cls) + table.dispatch.before_parent_attach(table, metadata) + metadata._add_table(name, schema, table) + try: + table.__init__(name, metadata, *args, _no_init=False, **kw) + table.dispatch.after_parent_attach(table, metadata) + return table + except Exception: + with util.safe_reraise(): + metadata._remove_table(name, schema) + + def __init__( + self, + name: str, + metadata: MetaData, + *args: SchemaItem, + schema: Optional[Union[str, Literal[SchemaConst.BLANK_SCHEMA]]] = None, + quote: Optional[bool] = None, + quote_schema: Optional[bool] = None, + autoload_with: Optional[Union[Engine, Connection]] = None, + autoload_replace: bool = True, + keep_existing: bool = False, + extend_existing: bool = False, + resolve_fks: bool = True, + include_columns: Optional[Collection[str]] = None, + implicit_returning: bool = True, + comment: Optional[str] = None, + info: Optional[Dict[Any, Any]] = None, + listeners: Optional[ + _typing_Sequence[Tuple[str, Callable[..., Any]]] + ] = None, + prefixes: Optional[_typing_Sequence[str]] = None, + # used internally in the metadata.reflect() process + _extend_on: Optional[Set[Table]] = None, + # used by __new__ to bypass __init__ + _no_init: bool = True, + # dialect-specific keyword args + **kw: Any, + ) -> None: + r"""Constructor for :class:`_schema.Table`. + + + :param name: The name of this table as represented in the database. + + The table name, along with the value of the ``schema`` parameter, + forms a key which uniquely identifies this :class:`_schema.Table` + within + the owning :class:`_schema.MetaData` collection. + Additional calls to :class:`_schema.Table` with the same name, + metadata, + and schema name will return the same :class:`_schema.Table` object. + + Names which contain no upper case characters + will be treated as case insensitive names, and will not be quoted + unless they are a reserved word or contain special characters. + A name with any number of upper case characters is considered + to be case sensitive, and will be sent as quoted. + + To enable unconditional quoting for the table name, specify the flag + ``quote=True`` to the constructor, or use the :class:`.quoted_name` + construct to specify the name. + + :param metadata: a :class:`_schema.MetaData` + object which will contain this + table. The metadata is used as a point of association of this table + with other tables which are referenced via foreign key. It also + may be used to associate this table with a particular + :class:`.Connection` or :class:`.Engine`. + + :param \*args: Additional positional arguments are used primarily + to add the list of :class:`_schema.Column` + objects contained within this + table. Similar to the style of a CREATE TABLE statement, other + :class:`.SchemaItem` constructs may be added here, including + :class:`.PrimaryKeyConstraint`, and + :class:`_schema.ForeignKeyConstraint`. + + :param autoload_replace: Defaults to ``True``; when using + :paramref:`_schema.Table.autoload_with` + in conjunction with :paramref:`_schema.Table.extend_existing`, + indicates + that :class:`_schema.Column` objects present in the already-existing + :class:`_schema.Table` + object should be replaced with columns of the same + name retrieved from the autoload process. When ``False``, columns + already present under existing names will be omitted from the + reflection process. + + Note that this setting does not impact :class:`_schema.Column` objects + specified programmatically within the call to :class:`_schema.Table` + that + also is autoloading; those :class:`_schema.Column` objects will always + replace existing columns of the same name when + :paramref:`_schema.Table.extend_existing` is ``True``. + + .. seealso:: + + :paramref:`_schema.Table.autoload_with` + + :paramref:`_schema.Table.extend_existing` + + :param autoload_with: An :class:`_engine.Engine` or + :class:`_engine.Connection` object, + or a :class:`_reflection.Inspector` object as returned by + :func:`_sa.inspect` + against one, with which this :class:`_schema.Table` + object will be reflected. + When set to a non-None value, the autoload process will take place + for this table against the given engine or connection. + + .. seealso:: + + :ref:`metadata_reflection_toplevel` + + :meth:`_events.DDLEvents.column_reflect` + + :ref:`metadata_reflection_dbagnostic_types` + + :param extend_existing: When ``True``, indicates that if this + :class:`_schema.Table` is already present in the given + :class:`_schema.MetaData`, + apply further arguments within the constructor to the existing + :class:`_schema.Table`. + + If :paramref:`_schema.Table.extend_existing` or + :paramref:`_schema.Table.keep_existing` are not set, + and the given name + of the new :class:`_schema.Table` refers to a :class:`_schema.Table` + that is + already present in the target :class:`_schema.MetaData` collection, + and + this :class:`_schema.Table` + specifies additional columns or other constructs + or flags that modify the table's state, an + error is raised. The purpose of these two mutually-exclusive flags + is to specify what action should be taken when a + :class:`_schema.Table` + is specified that matches an existing :class:`_schema.Table`, + yet specifies + additional constructs. + + :paramref:`_schema.Table.extend_existing` + will also work in conjunction + with :paramref:`_schema.Table.autoload_with` to run a new reflection + operation against the database, even if a :class:`_schema.Table` + of the same name is already present in the target + :class:`_schema.MetaData`; newly reflected :class:`_schema.Column` + objects + and other options will be added into the state of the + :class:`_schema.Table`, potentially overwriting existing columns + and options of the same name. + + As is always the case with :paramref:`_schema.Table.autoload_with`, + :class:`_schema.Column` objects can be specified in the same + :class:`_schema.Table` + constructor, which will take precedence. Below, the existing + table ``mytable`` will be augmented with :class:`_schema.Column` + objects + both reflected from the database, as well as the given + :class:`_schema.Column` + named "y":: + + Table("mytable", metadata, + Column('y', Integer), + extend_existing=True, + autoload_with=engine + ) + + .. seealso:: + + :paramref:`_schema.Table.autoload_with` + + :paramref:`_schema.Table.autoload_replace` + + :paramref:`_schema.Table.keep_existing` + + + :param implicit_returning: True by default - indicates that + RETURNING can be used, typically by the ORM, in order to fetch + server-generated values such as primary key values and + server side defaults, on those backends which support RETURNING. + + In modern SQLAlchemy there is generally no reason to alter this + setting, except for some backend specific cases + (see :ref:`mssql_triggers` in the SQL Server dialect documentation + for one such example). + + :param include_columns: A list of strings indicating a subset of + columns to be loaded via the ``autoload`` operation; table columns who + aren't present in this list will not be represented on the resulting + ``Table`` object. Defaults to ``None`` which indicates all columns + should be reflected. + + :param resolve_fks: Whether or not to reflect :class:`_schema.Table` + objects + related to this one via :class:`_schema.ForeignKey` objects, when + :paramref:`_schema.Table.autoload_with` is + specified. Defaults to True. Set to False to disable reflection of + related tables as :class:`_schema.ForeignKey` + objects are encountered; may be + used either to save on SQL calls or to avoid issues with related tables + that can't be accessed. Note that if a related table is already present + in the :class:`_schema.MetaData` collection, or becomes present later, + a + :class:`_schema.ForeignKey` object associated with this + :class:`_schema.Table` will + resolve to that table normally. + + .. versionadded:: 1.3 + + .. seealso:: + + :paramref:`.MetaData.reflect.resolve_fks` + + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + :param keep_existing: When ``True``, indicates that if this Table + is already present in the given :class:`_schema.MetaData`, ignore + further arguments within the constructor to the existing + :class:`_schema.Table`, and return the :class:`_schema.Table` + object as + originally created. This is to allow a function that wishes + to define a new :class:`_schema.Table` on first call, but on + subsequent calls will return the same :class:`_schema.Table`, + without any of the declarations (particularly constraints) + being applied a second time. + + If :paramref:`_schema.Table.extend_existing` or + :paramref:`_schema.Table.keep_existing` are not set, + and the given name + of the new :class:`_schema.Table` refers to a :class:`_schema.Table` + that is + already present in the target :class:`_schema.MetaData` collection, + and + this :class:`_schema.Table` + specifies additional columns or other constructs + or flags that modify the table's state, an + error is raised. The purpose of these two mutually-exclusive flags + is to specify what action should be taken when a + :class:`_schema.Table` + is specified that matches an existing :class:`_schema.Table`, + yet specifies + additional constructs. + + .. seealso:: + + :paramref:`_schema.Table.extend_existing` + + :param listeners: A list of tuples of the form ``(<eventname>, <fn>)`` + which will be passed to :func:`.event.listen` upon construction. + This alternate hook to :func:`.event.listen` allows the establishment + of a listener function specific to this :class:`_schema.Table` before + the "autoload" process begins. Historically this has been intended + for use with the :meth:`.DDLEvents.column_reflect` event, however + note that this event hook may now be associated with the + :class:`_schema.MetaData` object directly:: + + def listen_for_reflect(table, column_info): + "handle the column reflection event" + # ... + + t = Table( + 'sometable', + autoload_with=engine, + listeners=[ + ('column_reflect', listen_for_reflect) + ]) + + .. seealso:: + + :meth:`_events.DDLEvents.column_reflect` + + :param must_exist: When ``True``, indicates that this Table must already + be present in the given :class:`_schema.MetaData` collection, else + an exception is raised. + + :param prefixes: + A list of strings to insert after CREATE in the CREATE TABLE + statement. They will be separated by spaces. + + :param quote: Force quoting of this table's name on or off, corresponding + to ``True`` or ``False``. When left at its default of ``None``, + the column identifier will be quoted according to whether the name is + case sensitive (identifiers with at least one upper case character are + treated as case sensitive), or if it's a reserved word. This flag + is only needed to force quoting of a reserved word which is not known + by the SQLAlchemy dialect. + + .. note:: setting this flag to ``False`` will not provide + case-insensitive behavior for table reflection; table reflection + will always search for a mixed-case name in a case sensitive + fashion. Case insensitive names are specified in SQLAlchemy only + by stating the name with all lower case characters. + + :param quote_schema: same as 'quote' but applies to the schema identifier. + + :param schema: The schema name for this table, which is required if + the table resides in a schema other than the default selected schema + for the engine's database connection. Defaults to ``None``. + + If the owning :class:`_schema.MetaData` of this :class:`_schema.Table` + specifies its + own :paramref:`_schema.MetaData.schema` parameter, + then that schema name will + be applied to this :class:`_schema.Table` + if the schema parameter here is set + to ``None``. To set a blank schema name on a :class:`_schema.Table` + that + would otherwise use the schema set on the owning + :class:`_schema.MetaData`, + specify the special symbol :attr:`.BLANK_SCHEMA`. + + The quoting rules for the schema name are the same as those for the + ``name`` parameter, in that quoting is applied for reserved words or + case-sensitive names; to enable unconditional quoting for the schema + name, specify the flag ``quote_schema=True`` to the constructor, or use + the :class:`.quoted_name` construct to specify the name. + + :param comment: Optional string that will render an SQL comment on table + creation. + + .. versionadded:: 1.2 Added the :paramref:`_schema.Table.comment` + parameter + to :class:`_schema.Table`. + + :param \**kw: Additional keyword arguments not mentioned above are + dialect specific, and passed in the form ``<dialectname>_<argname>``. + See the documentation regarding an individual dialect at + :ref:`dialect_toplevel` for detail on documented arguments. + + """ # noqa: E501 + if _no_init: + # don't run __init__ from __new__ by default; + # __new__ has a specific place that __init__ is called + return + + super().__init__(quoted_name(name, quote)) + self.metadata = metadata + + if schema is None: + self.schema = metadata.schema + elif schema is BLANK_SCHEMA: + self.schema = None + else: + quote_schema = quote_schema + assert isinstance(schema, str) + self.schema = quoted_name(schema, quote_schema) + + self._sentinel_column = None + + self.indexes = set() + self.constraints = set() + PrimaryKeyConstraint( + _implicit_generated=True + )._set_parent_with_dispatch(self) + self.foreign_keys = set() # type: ignore + self._extra_dependencies: Set[Table] = set() + if self.schema is not None: + self.fullname = "%s.%s" % (self.schema, self.name) + else: + self.fullname = self.name + + self.implicit_returning = implicit_returning + _reflect_info = kw.pop("_reflect_info", None) + + self.comment = comment + + if info is not None: + self.info = info + + if listeners is not None: + for evt, fn in listeners: + event.listen(self, evt, fn) + + self._prefixes = prefixes if prefixes else [] + + self._extra_kwargs(**kw) + + # load column definitions from the database if 'autoload' is defined + # we do it after the table is in the singleton dictionary to support + # circular foreign keys + if autoload_with is not None: + self._autoload( + metadata, + autoload_with, + include_columns, + _extend_on=_extend_on, + _reflect_info=_reflect_info, + resolve_fks=resolve_fks, + ) + + # initialize all the column, etc. objects. done after reflection to + # allow user-overrides + + self._init_items( + *args, + allow_replacements=extend_existing + or keep_existing + or autoload_with, + all_names={}, + ) + + def _autoload( + self, + metadata: MetaData, + autoload_with: Union[Engine, Connection], + include_columns: Optional[Collection[str]], + exclude_columns: Collection[str] = (), + resolve_fks: bool = True, + _extend_on: Optional[Set[Table]] = None, + _reflect_info: _ReflectionInfo | None = None, + ) -> None: + insp = inspection.inspect(autoload_with) + with insp._inspection_context() as conn_insp: + conn_insp.reflect_table( + self, + include_columns, + exclude_columns, + resolve_fks, + _extend_on=_extend_on, + _reflect_info=_reflect_info, + ) + + @property + def _sorted_constraints(self) -> List[Constraint]: + """Return the set of constraints as a list, sorted by creation + order. + + """ + + return sorted(self.constraints, key=lambda c: c._creation_order) + + @property + def foreign_key_constraints(self) -> Set[ForeignKeyConstraint]: + """:class:`_schema.ForeignKeyConstraint` objects referred to by this + :class:`_schema.Table`. + + This list is produced from the collection of + :class:`_schema.ForeignKey` + objects currently associated. + + + .. seealso:: + + :attr:`_schema.Table.constraints` + + :attr:`_schema.Table.foreign_keys` + + :attr:`_schema.Table.indexes` + + """ + return { + fkc.constraint + for fkc in self.foreign_keys + if fkc.constraint is not None + } + + def _init_existing(self, *args: Any, **kwargs: Any) -> None: + autoload_with = kwargs.pop("autoload_with", None) + autoload = kwargs.pop("autoload", autoload_with is not None) + autoload_replace = kwargs.pop("autoload_replace", True) + schema = kwargs.pop("schema", None) + _extend_on = kwargs.pop("_extend_on", None) + _reflect_info = kwargs.pop("_reflect_info", None) + + # these arguments are only used with _init() + extend_existing = kwargs.pop("extend_existing", False) + keep_existing = kwargs.pop("keep_existing", False) + + assert extend_existing + assert not keep_existing + + if schema and schema != self.schema: + raise exc.ArgumentError( + f"Can't change schema of existing table " + f"from '{self.schema}' to '{schema}'", + ) + + include_columns = kwargs.pop("include_columns", None) + if include_columns is not None: + for c in self.c: + if c.name not in include_columns: + self._columns.remove(c) + + resolve_fks = kwargs.pop("resolve_fks", True) + + for key in ("quote", "quote_schema"): + if key in kwargs: + raise exc.ArgumentError( + "Can't redefine 'quote' or 'quote_schema' arguments" + ) + + # update `self` with these kwargs, if provided + self.comment = kwargs.pop("comment", self.comment) + self.implicit_returning = kwargs.pop( + "implicit_returning", self.implicit_returning + ) + self.info = kwargs.pop("info", self.info) + + exclude_columns: _typing_Sequence[str] + + if autoload: + if not autoload_replace: + # don't replace columns already present. + # we'd like to do this for constraints also however we don't + # have simple de-duping for unnamed constraints. + exclude_columns = [c.name for c in self.c] + else: + exclude_columns = () + self._autoload( + self.metadata, + autoload_with, + include_columns, + exclude_columns, + resolve_fks, + _extend_on=_extend_on, + _reflect_info=_reflect_info, + ) + + all_names = {c.name: c for c in self.c} + self._extra_kwargs(**kwargs) + self._init_items(*args, allow_replacements=True, all_names=all_names) + + def _extra_kwargs(self, **kwargs: Any) -> None: + self._validate_dialect_kwargs(kwargs) + + def _init_collections(self) -> None: + pass + + def _reset_exported(self) -> None: + pass + + @util.ro_non_memoized_property + def _autoincrement_column(self) -> Optional[Column[int]]: + return self.primary_key._autoincrement_column + + @util.ro_memoized_property + def _sentinel_column_characteristics( + self, + ) -> _SentinelColumnCharacterization: + """determine a candidate column (or columns, in case of a client + generated composite primary key) which can be used as an + "insert sentinel" for an INSERT statement. + + The returned structure, :class:`_SentinelColumnCharacterization`, + includes all the details needed by :class:`.Dialect` and + :class:`.SQLCompiler` to determine if these column(s) can be used + as an INSERT..RETURNING sentinel for a particular database + dialect. + + .. versionadded:: 2.0.10 + + """ + + sentinel_is_explicit = False + sentinel_is_autoinc = False + the_sentinel: Optional[_typing_Sequence[Column[Any]]] = None + + # see if a column was explicitly marked "insert_sentinel=True". + explicit_sentinel_col = self._sentinel_column + + if explicit_sentinel_col is not None: + the_sentinel = (explicit_sentinel_col,) + sentinel_is_explicit = True + + autoinc_col = self._autoincrement_column + if sentinel_is_explicit and explicit_sentinel_col is autoinc_col: + assert autoinc_col is not None + sentinel_is_autoinc = True + elif explicit_sentinel_col is None and autoinc_col is not None: + the_sentinel = (autoinc_col,) + sentinel_is_autoinc = True + + default_characterization = _SentinelDefaultCharacterization.UNKNOWN + + if the_sentinel: + the_sentinel_zero = the_sentinel[0] + if the_sentinel_zero.identity: + if the_sentinel_zero.identity._increment_is_negative: + if sentinel_is_explicit: + raise exc.InvalidRequestError( + "Can't use IDENTITY default with negative " + "increment as an explicit sentinel column" + ) + else: + if sentinel_is_autoinc: + autoinc_col = None + sentinel_is_autoinc = False + the_sentinel = None + else: + default_characterization = ( + _SentinelDefaultCharacterization.IDENTITY + ) + elif ( + the_sentinel_zero.default is None + and the_sentinel_zero.server_default is None + ): + if the_sentinel_zero.nullable: + raise exc.InvalidRequestError( + f"Column {the_sentinel_zero} has been marked as a " + "sentinel " + "column with no default generation function; it " + "at least needs to be marked nullable=False assuming " + "user-populated sentinel values will be used." + ) + default_characterization = ( + _SentinelDefaultCharacterization.NONE + ) + elif the_sentinel_zero.default is not None: + if the_sentinel_zero.default.is_sentinel: + default_characterization = ( + _SentinelDefaultCharacterization.SENTINEL_DEFAULT + ) + elif default_is_sequence(the_sentinel_zero.default): + if the_sentinel_zero.default._increment_is_negative: + if sentinel_is_explicit: + raise exc.InvalidRequestError( + "Can't use SEQUENCE default with negative " + "increment as an explicit sentinel column" + ) + else: + if sentinel_is_autoinc: + autoinc_col = None + sentinel_is_autoinc = False + the_sentinel = None + + default_characterization = ( + _SentinelDefaultCharacterization.SEQUENCE + ) + elif the_sentinel_zero.default.is_callable: + default_characterization = ( + _SentinelDefaultCharacterization.CLIENTSIDE + ) + elif the_sentinel_zero.server_default is not None: + if sentinel_is_explicit: + raise exc.InvalidRequestError( + f"Column {the_sentinel[0]} can't be a sentinel column " + "because it uses an explicit server side default " + "that's not the Identity() default." + ) + + default_characterization = ( + _SentinelDefaultCharacterization.SERVERSIDE + ) + + if the_sentinel is None and self.primary_key: + assert autoinc_col is None + + # determine for non-autoincrement pk if all elements are + # client side + for _pkc in self.primary_key: + if _pkc.server_default is not None or ( + _pkc.default and not _pkc.default.is_callable + ): + break + else: + the_sentinel = tuple(self.primary_key) + default_characterization = ( + _SentinelDefaultCharacterization.CLIENTSIDE + ) + + return _SentinelColumnCharacterization( + the_sentinel, + sentinel_is_explicit, + sentinel_is_autoinc, + default_characterization, + ) + + @property + def autoincrement_column(self) -> Optional[Column[int]]: + """Returns the :class:`.Column` object which currently represents + the "auto increment" column, if any, else returns None. + + This is based on the rules for :class:`.Column` as defined by the + :paramref:`.Column.autoincrement` parameter, which generally means the + column within a single integer column primary key constraint that is + not constrained by a foreign key. If the table does not have such + a primary key constraint, then there's no "autoincrement" column. + A :class:`.Table` may have only one column defined as the + "autoincrement" column. + + .. versionadded:: 2.0.4 + + .. seealso:: + + :paramref:`.Column.autoincrement` + + """ + return self._autoincrement_column + + @property + def key(self) -> str: + """Return the 'key' for this :class:`_schema.Table`. + + This value is used as the dictionary key within the + :attr:`_schema.MetaData.tables` collection. It is typically the same + as that of :attr:`_schema.Table.name` for a table with no + :attr:`_schema.Table.schema` + set; otherwise it is typically of the form + ``schemaname.tablename``. + + """ + return _get_table_key(self.name, self.schema) + + def __repr__(self) -> str: + return "Table(%s)" % ", ".join( + [repr(self.name)] + + [repr(self.metadata)] + + [repr(x) for x in self.columns] + + ["%s=%s" % (k, repr(getattr(self, k))) for k in ["schema"]] + ) + + def __str__(self) -> str: + return _get_table_key(self.description, self.schema) + + def add_is_dependent_on(self, table: Table) -> None: + """Add a 'dependency' for this Table. + + This is another Table object which must be created + first before this one can, or dropped after this one. + + Usually, dependencies between tables are determined via + ForeignKey objects. However, for other situations that + create dependencies outside of foreign keys (rules, inheriting), + this method can manually establish such a link. + + """ + self._extra_dependencies.add(table) + + def append_column( + self, column: ColumnClause[Any], replace_existing: bool = False + ) -> None: + """Append a :class:`_schema.Column` to this :class:`_schema.Table`. + + The "key" of the newly added :class:`_schema.Column`, i.e. the + value of its ``.key`` attribute, will then be available + in the ``.c`` collection of this :class:`_schema.Table`, and the + column definition will be included in any CREATE TABLE, SELECT, + UPDATE, etc. statements generated from this :class:`_schema.Table` + construct. + + Note that this does **not** change the definition of the table + as it exists within any underlying database, assuming that + table has already been created in the database. Relational + databases support the addition of columns to existing tables + using the SQL ALTER command, which would need to be + emitted for an already-existing table that doesn't contain + the newly added column. + + :param replace_existing: When ``True``, allows replacing existing + columns. When ``False``, the default, an warning will be raised + if a column with the same ``.key`` already exists. A future + version of sqlalchemy will instead rise a warning. + + .. versionadded:: 1.4.0 + """ + + try: + column._set_parent_with_dispatch( + self, + allow_replacements=replace_existing, + all_names={c.name: c for c in self.c}, + ) + except exc.DuplicateColumnError as de: + raise exc.DuplicateColumnError( + f"{de.args[0]} Specify replace_existing=True to " + "Table.append_column() to replace an " + "existing column." + ) from de + + def append_constraint(self, constraint: Union[Index, Constraint]) -> None: + """Append a :class:`_schema.Constraint` to this + :class:`_schema.Table`. + + This has the effect of the constraint being included in any + future CREATE TABLE statement, assuming specific DDL creation + events have not been associated with the given + :class:`_schema.Constraint` object. + + Note that this does **not** produce the constraint within the + relational database automatically, for a table that already exists + in the database. To add a constraint to an + existing relational database table, the SQL ALTER command must + be used. SQLAlchemy also provides the + :class:`.AddConstraint` construct which can produce this SQL when + invoked as an executable clause. + + """ + + constraint._set_parent_with_dispatch(self) + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + metadata = parent + assert isinstance(metadata, MetaData) + metadata._add_table(self.name, self.schema, self) + self.metadata = metadata + + def create(self, bind: _CreateDropBind, checkfirst: bool = False) -> None: + """Issue a ``CREATE`` statement for this + :class:`_schema.Table`, using the given + :class:`.Connection` or :class:`.Engine` + for connectivity. + + .. seealso:: + + :meth:`_schema.MetaData.create_all`. + + """ + + bind._run_ddl_visitor(ddl.SchemaGenerator, self, checkfirst=checkfirst) + + def drop(self, bind: _CreateDropBind, checkfirst: bool = False) -> None: + """Issue a ``DROP`` statement for this + :class:`_schema.Table`, using the given + :class:`.Connection` or :class:`.Engine` for connectivity. + + .. seealso:: + + :meth:`_schema.MetaData.drop_all`. + + """ + bind._run_ddl_visitor(ddl.SchemaDropper, self, checkfirst=checkfirst) + + @util.deprecated( + "1.4", + ":meth:`_schema.Table.tometadata` is renamed to " + ":meth:`_schema.Table.to_metadata`", + ) + def tometadata( + self, + metadata: MetaData, + schema: Union[str, Literal[SchemaConst.RETAIN_SCHEMA]] = RETAIN_SCHEMA, + referred_schema_fn: Optional[ + Callable[ + [Table, Optional[str], ForeignKeyConstraint, Optional[str]], + Optional[str], + ] + ] = None, + name: Optional[str] = None, + ) -> Table: + """Return a copy of this :class:`_schema.Table` + associated with a different + :class:`_schema.MetaData`. + + See :meth:`_schema.Table.to_metadata` for a full description. + + """ + return self.to_metadata( + metadata, + schema=schema, + referred_schema_fn=referred_schema_fn, + name=name, + ) + + def to_metadata( + self, + metadata: MetaData, + schema: Union[str, Literal[SchemaConst.RETAIN_SCHEMA]] = RETAIN_SCHEMA, + referred_schema_fn: Optional[ + Callable[ + [Table, Optional[str], ForeignKeyConstraint, Optional[str]], + Optional[str], + ] + ] = None, + name: Optional[str] = None, + ) -> Table: + """Return a copy of this :class:`_schema.Table` associated with a + different :class:`_schema.MetaData`. + + E.g.:: + + m1 = MetaData() + + user = Table('user', m1, Column('id', Integer, primary_key=True)) + + m2 = MetaData() + user_copy = user.to_metadata(m2) + + .. versionchanged:: 1.4 The :meth:`_schema.Table.to_metadata` function + was renamed from :meth:`_schema.Table.tometadata`. + + + :param metadata: Target :class:`_schema.MetaData` object, + into which the + new :class:`_schema.Table` object will be created. + + :param schema: optional string name indicating the target schema. + Defaults to the special symbol :attr:`.RETAIN_SCHEMA` which indicates + that no change to the schema name should be made in the new + :class:`_schema.Table`. If set to a string name, the new + :class:`_schema.Table` + will have this new name as the ``.schema``. If set to ``None``, the + schema will be set to that of the schema set on the target + :class:`_schema.MetaData`, which is typically ``None`` as well, + unless + set explicitly:: + + m2 = MetaData(schema='newschema') + + # user_copy_one will have "newschema" as the schema name + user_copy_one = user.to_metadata(m2, schema=None) + + m3 = MetaData() # schema defaults to None + + # user_copy_two will have None as the schema name + user_copy_two = user.to_metadata(m3, schema=None) + + :param referred_schema_fn: optional callable which can be supplied + in order to provide for the schema name that should be assigned + to the referenced table of a :class:`_schema.ForeignKeyConstraint`. + The callable accepts this parent :class:`_schema.Table`, the + target schema that we are changing to, the + :class:`_schema.ForeignKeyConstraint` object, and the existing + "target schema" of that constraint. The function should return the + string schema name that should be applied. To reset the schema + to "none", return the symbol :data:`.BLANK_SCHEMA`. To effect no + change, return ``None`` or :data:`.RETAIN_SCHEMA`. + + .. versionchanged:: 1.4.33 The ``referred_schema_fn`` function + may return the :data:`.BLANK_SCHEMA` or :data:`.RETAIN_SCHEMA` + symbols. + + E.g.:: + + def referred_schema_fn(table, to_schema, + constraint, referred_schema): + if referred_schema == 'base_tables': + return referred_schema + else: + return to_schema + + new_table = table.to_metadata(m2, schema="alt_schema", + referred_schema_fn=referred_schema_fn) + + :param name: optional string name indicating the target table name. + If not specified or None, the table name is retained. This allows + a :class:`_schema.Table` to be copied to the same + :class:`_schema.MetaData` target + with a new name. + + """ + if name is None: + name = self.name + + actual_schema: Optional[str] + + if schema is RETAIN_SCHEMA: + actual_schema = self.schema + elif schema is None: + actual_schema = metadata.schema + else: + actual_schema = schema + key = _get_table_key(name, actual_schema) + if key in metadata.tables: + util.warn( + f"Table '{self.description}' already exists within the given " + "MetaData - not copying." + ) + return metadata.tables[key] + + args = [] + for col in self.columns: + args.append(col._copy(schema=actual_schema)) + table = Table( + name, + metadata, + schema=actual_schema, + comment=self.comment, + *args, + **self.kwargs, + ) + for const in self.constraints: + if isinstance(const, ForeignKeyConstraint): + referred_schema = const._referred_schema + if referred_schema_fn: + fk_constraint_schema = referred_schema_fn( + self, actual_schema, const, referred_schema + ) + else: + fk_constraint_schema = ( + actual_schema + if referred_schema == self.schema + else None + ) + table.append_constraint( + const._copy( + schema=fk_constraint_schema, target_table=table + ) + ) + elif not const._type_bound: + # skip unique constraints that would be generated + # by the 'unique' flag on Column + if const._column_flag: + continue + + table.append_constraint( + const._copy(schema=actual_schema, target_table=table) + ) + for index in self.indexes: + # skip indexes that would be generated + # by the 'index' flag on Column + if index._column_flag: + continue + Index( + index.name, + unique=index.unique, + *[ + _copy_expression(expr, self, table) + for expr in index._table_bound_expressions + ], + _table=table, + **index.kwargs, + ) + return self._schema_item_copy(table) + + +class Column(DialectKWArgs, SchemaItem, ColumnClause[_T]): + """Represents a column in a database table.""" + + __visit_name__ = "column" + + inherit_cache = True + key: str + + server_default: Optional[FetchedValue] + + def __init__( + self, + __name_pos: Optional[ + Union[str, _TypeEngineArgument[_T], SchemaEventTarget] + ] = None, + __type_pos: Optional[ + Union[_TypeEngineArgument[_T], SchemaEventTarget] + ] = None, + *args: SchemaEventTarget, + name: Optional[str] = None, + type_: Optional[_TypeEngineArgument[_T]] = None, + autoincrement: _AutoIncrementType = "auto", + default: Optional[Any] = None, + doc: Optional[str] = None, + key: Optional[str] = None, + index: Optional[bool] = None, + unique: Optional[bool] = None, + info: Optional[_InfoType] = None, + nullable: Optional[ + Union[bool, Literal[SchemaConst.NULL_UNSPECIFIED]] + ] = SchemaConst.NULL_UNSPECIFIED, + onupdate: Optional[Any] = None, + primary_key: bool = False, + server_default: Optional[_ServerDefaultArgument] = None, + server_onupdate: Optional[FetchedValue] = None, + quote: Optional[bool] = None, + system: bool = False, + comment: Optional[str] = None, + insert_sentinel: bool = False, + _omit_from_statements: bool = False, + _proxies: Optional[Any] = None, + **dialect_kwargs: Any, + ): + r""" + Construct a new ``Column`` object. + + :param name: The name of this column as represented in the database. + This argument may be the first positional argument, or specified + via keyword. + + Names which contain no upper case characters + will be treated as case insensitive names, and will not be quoted + unless they are a reserved word. Names with any number of upper + case characters will be quoted and sent exactly. Note that this + behavior applies even for databases which standardize upper + case names as case insensitive such as Oracle. + + The name field may be omitted at construction time and applied + later, at any time before the Column is associated with a + :class:`_schema.Table`. This is to support convenient + usage within the :mod:`~sqlalchemy.ext.declarative` extension. + + :param type\_: The column's type, indicated using an instance which + subclasses :class:`~sqlalchemy.types.TypeEngine`. If no arguments + are required for the type, the class of the type can be sent + as well, e.g.:: + + # use a type with arguments + Column('data', String(50)) + + # use no arguments + Column('level', Integer) + + The ``type`` argument may be the second positional argument + or specified by keyword. + + If the ``type`` is ``None`` or is omitted, it will first default to + the special type :class:`.NullType`. If and when this + :class:`_schema.Column` is made to refer to another column using + :class:`_schema.ForeignKey` and/or + :class:`_schema.ForeignKeyConstraint`, the type + of the remote-referenced column will be copied to this column as + well, at the moment that the foreign key is resolved against that + remote :class:`_schema.Column` object. + + :param \*args: Additional positional arguments include various + :class:`.SchemaItem` derived constructs which will be applied + as options to the column. These include instances of + :class:`.Constraint`, :class:`_schema.ForeignKey`, + :class:`.ColumnDefault`, :class:`.Sequence`, :class:`.Computed` + :class:`.Identity`. In some cases an + equivalent keyword argument is available such as ``server_default``, + ``default`` and ``unique``. + + :param autoincrement: Set up "auto increment" semantics for an + **integer primary key column with no foreign key dependencies** + (see later in this docstring for a more specific definition). + This may influence the :term:`DDL` that will be emitted for + this column during a table create, as well as how the column + will be considered when INSERT statements are compiled and + executed. + + The default value is the string ``"auto"``, + which indicates that a single-column (i.e. non-composite) primary key + that is of an INTEGER type with no other client-side or server-side + default constructs indicated should receive auto increment semantics + automatically. Other values include ``True`` (force this column to + have auto-increment semantics for a :term:`composite primary key` as + well), ``False`` (this column should never have auto-increment + semantics), and the string ``"ignore_fk"`` (special-case for foreign + key columns, see below). + + The term "auto increment semantics" refers both to the kind of DDL + that will be emitted for the column within a CREATE TABLE statement, + when methods such as :meth:`.MetaData.create_all` and + :meth:`.Table.create` are invoked, as well as how the column will be + considered when an INSERT statement is compiled and emitted to the + database: + + * **DDL rendering** (i.e. :meth:`.MetaData.create_all`, + :meth:`.Table.create`): When used on a :class:`.Column` that has + no other + default-generating construct associated with it (such as a + :class:`.Sequence` or :class:`.Identity` construct), the parameter + will imply that database-specific keywords such as PostgreSQL + ``SERIAL``, MySQL ``AUTO_INCREMENT``, or ``IDENTITY`` on SQL Server + should also be rendered. Not every database backend has an + "implied" default generator available; for example the Oracle + backend always needs an explicit construct such as + :class:`.Identity` to be included with a :class:`.Column` in order + for the DDL rendered to include auto-generating constructs to also + be produced in the database. + + * **INSERT semantics** (i.e. when a :func:`_sql.insert` construct is + compiled into a SQL string and is then executed on a database using + :meth:`_engine.Connection.execute` or equivalent): A single-row + INSERT statement will be known to produce a new integer primary key + value automatically for this column, which will be accessible + after the statement is invoked via the + :attr:`.CursorResult.inserted_primary_key` attribute upon the + :class:`_result.Result` object. This also applies towards use of the + ORM when ORM-mapped objects are persisted to the database, + indicating that a new integer primary key will be available to + become part of the :term:`identity key` for that object. This + behavior takes place regardless of what DDL constructs are + associated with the :class:`_schema.Column` and is independent + of the "DDL Rendering" behavior discussed in the previous note + above. + + The parameter may be set to ``True`` to indicate that a column which + is part of a composite (i.e. multi-column) primary key should + have autoincrement semantics, though note that only one column + within a primary key may have this setting. It can also + be set to ``True`` to indicate autoincrement semantics on a + column that has a client-side or server-side default configured, + however note that not all dialects can accommodate all styles + of default as an "autoincrement". It can also be + set to ``False`` on a single-column primary key that has a + datatype of INTEGER in order to disable auto increment semantics + for that column. + + The setting *only* has an effect for columns which are: + + * Integer derived (i.e. INT, SMALLINT, BIGINT). + + * Part of the primary key + + * Not referring to another column via :class:`_schema.ForeignKey`, + unless + the value is specified as ``'ignore_fk'``:: + + # turn on autoincrement for this column despite + # the ForeignKey() + Column('id', ForeignKey('other.id'), + primary_key=True, autoincrement='ignore_fk') + + It is typically not desirable to have "autoincrement" enabled on a + column that refers to another via foreign key, as such a column is + required to refer to a value that originates from elsewhere. + + The setting has these effects on columns that meet the + above criteria: + + * DDL issued for the column, if the column does not already include + a default generating construct supported by the backend such as + :class:`.Identity`, will include database-specific + keywords intended to signify this column as an + "autoincrement" column for specific backends. Behavior for + primary SQLAlchemy dialects includes: + + * AUTO INCREMENT on MySQL and MariaDB + * SERIAL on PostgreSQL + * IDENTITY on MS-SQL - this occurs even without the + :class:`.Identity` construct as the + :paramref:`.Column.autoincrement` parameter pre-dates this + construct. + * SQLite - SQLite integer primary key columns are implicitly + "auto incrementing" and no additional keywords are rendered; + to render the special SQLite keyword ``AUTOINCREMENT`` + is not included as this is unnecessary and not recommended + by the database vendor. See the section + :ref:`sqlite_autoincrement` for more background. + * Oracle - The Oracle dialect has no default "autoincrement" + feature available at this time, instead the :class:`.Identity` + construct is recommended to achieve this (the :class:`.Sequence` + construct may also be used). + * Third-party dialects - consult those dialects' documentation + for details on their specific behaviors. + + * When a single-row :func:`_sql.insert` construct is compiled and + executed, which does not set the :meth:`_sql.Insert.inline` + modifier, newly generated primary key values for this column + will be automatically retrieved upon statement execution + using a method specific to the database driver in use: + + * MySQL, SQLite - calling upon ``cursor.lastrowid()`` + (see + `https://www.python.org/dev/peps/pep-0249/#lastrowid + <https://www.python.org/dev/peps/pep-0249/#lastrowid>`_) + * PostgreSQL, SQL Server, Oracle - use RETURNING or an equivalent + construct when rendering an INSERT statement, and then retrieving + the newly generated primary key values after execution + * PostgreSQL, Oracle for :class:`_schema.Table` objects that + set :paramref:`_schema.Table.implicit_returning` to False - + for a :class:`.Sequence` only, the :class:`.Sequence` is invoked + explicitly before the INSERT statement takes place so that the + newly generated primary key value is available to the client + * SQL Server for :class:`_schema.Table` objects that + set :paramref:`_schema.Table.implicit_returning` to False - + the ``SELECT scope_identity()`` construct is used after the + INSERT statement is invoked to retrieve the newly generated + primary key value. + * Third-party dialects - consult those dialects' documentation + for details on their specific behaviors. + + * For multiple-row :func:`_sql.insert` constructs invoked with + a list of parameters (i.e. "executemany" semantics), primary-key + retrieving behaviors are generally disabled, however there may + be special APIs that may be used to retrieve lists of new + primary key values for an "executemany", such as the psycopg2 + "fast insertmany" feature. Such features are very new and + may not yet be well covered in documentation. + + :param default: A scalar, Python callable, or + :class:`_expression.ColumnElement` expression representing the + *default value* for this column, which will be invoked upon insert + if this column is otherwise not specified in the VALUES clause of + the insert. This is a shortcut to using :class:`.ColumnDefault` as + a positional argument; see that class for full detail on the + structure of the argument. + + Contrast this argument to + :paramref:`_schema.Column.server_default` + which creates a default generator on the database side. + + .. seealso:: + + :ref:`metadata_defaults_toplevel` + + :param doc: optional String that can be used by the ORM or similar + to document attributes on the Python side. This attribute does + **not** render SQL comments; use the + :paramref:`_schema.Column.comment` + parameter for this purpose. + + :param key: An optional string identifier which will identify this + ``Column`` object on the :class:`_schema.Table`. + When a key is provided, + this is the only identifier referencing the ``Column`` within the + application, including ORM attribute mapping; the ``name`` field + is used only when rendering SQL. + + :param index: When ``True``, indicates that a :class:`_schema.Index` + construct will be automatically generated for this + :class:`_schema.Column`, which will result in a "CREATE INDEX" + statement being emitted for the :class:`_schema.Table` when the DDL + create operation is invoked. + + Using this flag is equivalent to making use of the + :class:`_schema.Index` construct explicitly at the level of the + :class:`_schema.Table` construct itself:: + + Table( + "some_table", + metadata, + Column("x", Integer), + Index("ix_some_table_x", "x") + ) + + To add the :paramref:`_schema.Index.unique` flag to the + :class:`_schema.Index`, set both the + :paramref:`_schema.Column.unique` and + :paramref:`_schema.Column.index` flags to True simultaneously, + which will have the effect of rendering the "CREATE UNIQUE INDEX" + DDL instruction instead of "CREATE INDEX". + + The name of the index is generated using the + :ref:`default naming convention <constraint_default_naming_convention>` + which for the :class:`_schema.Index` construct is of the form + ``ix_<tablename>_<columnname>``. + + As this flag is intended only as a convenience for the common case + of adding a single-column, default configured index to a table + definition, explicit use of the :class:`_schema.Index` construct + should be preferred for most use cases, including composite indexes + that encompass more than one column, indexes with SQL expressions + or ordering, backend-specific index configuration options, and + indexes that use a specific name. + + .. note:: the :attr:`_schema.Column.index` attribute on + :class:`_schema.Column` + **does not indicate** if this column is indexed or not, only + if this flag was explicitly set here. To view indexes on + a column, view the :attr:`_schema.Table.indexes` collection + or use :meth:`_reflection.Inspector.get_indexes`. + + .. seealso:: + + :ref:`schema_indexes` + + :ref:`constraint_naming_conventions` + + :paramref:`_schema.Column.unique` + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + :param nullable: When set to ``False``, will cause the "NOT NULL" + phrase to be added when generating DDL for the column. When + ``True``, will normally generate nothing (in SQL this defaults to + "NULL"), except in some very specific backend-specific edge cases + where "NULL" may render explicitly. + Defaults to ``True`` unless :paramref:`_schema.Column.primary_key` + is also ``True`` or the column specifies a :class:`_sql.Identity`, + in which case it defaults to ``False``. + This parameter is only used when issuing CREATE TABLE statements. + + .. note:: + + When the column specifies a :class:`_sql.Identity` this + parameter is in general ignored by the DDL compiler. The + PostgreSQL database allows nullable identity column by + setting this parameter to ``True`` explicitly. + + :param onupdate: A scalar, Python callable, or + :class:`~sqlalchemy.sql.expression.ClauseElement` representing a + default value to be applied to the column within UPDATE + statements, which will be invoked upon update if this column is not + present in the SET clause of the update. This is a shortcut to + using :class:`.ColumnDefault` as a positional argument with + ``for_update=True``. + + .. seealso:: + + :ref:`metadata_defaults` - complete discussion of onupdate + + :param primary_key: If ``True``, marks this column as a primary key + column. Multiple columns can have this flag set to specify + composite primary keys. As an alternative, the primary key of a + :class:`_schema.Table` can be specified via an explicit + :class:`.PrimaryKeyConstraint` object. + + :param server_default: A :class:`.FetchedValue` instance, str, Unicode + or :func:`~sqlalchemy.sql.expression.text` construct representing + the DDL DEFAULT value for the column. + + String types will be emitted as-is, surrounded by single quotes:: + + Column('x', Text, server_default="val") + + x TEXT DEFAULT 'val' + + A :func:`~sqlalchemy.sql.expression.text` expression will be + rendered as-is, without quotes:: + + Column('y', DateTime, server_default=text('NOW()')) + + y DATETIME DEFAULT NOW() + + Strings and text() will be converted into a + :class:`.DefaultClause` object upon initialization. + + This parameter can also accept complex combinations of contextually + valid SQLAlchemy expressions or constructs:: + + from sqlalchemy import create_engine + from sqlalchemy import Table, Column, MetaData, ARRAY, Text + from sqlalchemy.dialects.postgresql import array + + engine = create_engine( + 'postgresql+psycopg2://scott:tiger@localhost/mydatabase' + ) + metadata_obj = MetaData() + tbl = Table( + "foo", + metadata_obj, + Column("bar", + ARRAY(Text), + server_default=array(["biz", "bang", "bash"]) + ) + ) + metadata_obj.create_all(engine) + + The above results in a table created with the following SQL:: + + CREATE TABLE foo ( + bar TEXT[] DEFAULT ARRAY['biz', 'bang', 'bash'] + ) + + Use :class:`.FetchedValue` to indicate that an already-existing + column will generate a default value on the database side which + will be available to SQLAlchemy for post-fetch after inserts. This + construct does not specify any DDL and the implementation is left + to the database, such as via a trigger. + + .. seealso:: + + :ref:`server_defaults` - complete discussion of server side + defaults + + :param server_onupdate: A :class:`.FetchedValue` instance + representing a database-side default generation function, + such as a trigger. This + indicates to SQLAlchemy that a newly generated value will be + available after updates. This construct does not actually + implement any kind of generation function within the database, + which instead must be specified separately. + + + .. warning:: This directive **does not** currently produce MySQL's + "ON UPDATE CURRENT_TIMESTAMP()" clause. See + :ref:`mysql_timestamp_onupdate` for background on how to + produce this clause. + + .. seealso:: + + :ref:`triggered_columns` + + :param quote: Force quoting of this column's name on or off, + corresponding to ``True`` or ``False``. When left at its default + of ``None``, the column identifier will be quoted according to + whether the name is case sensitive (identifiers with at least one + upper case character are treated as case sensitive), or if it's a + reserved word. This flag is only needed to force quoting of a + reserved word which is not known by the SQLAlchemy dialect. + + :param unique: When ``True``, and the :paramref:`_schema.Column.index` + parameter is left at its default value of ``False``, + indicates that a :class:`_schema.UniqueConstraint` + construct will be automatically generated for this + :class:`_schema.Column`, + which will result in a "UNIQUE CONSTRAINT" clause referring + to this column being included + in the ``CREATE TABLE`` statement emitted, when the DDL create + operation for the :class:`_schema.Table` object is invoked. + + When this flag is ``True`` while the + :paramref:`_schema.Column.index` parameter is simultaneously + set to ``True``, the effect instead is that a + :class:`_schema.Index` construct which includes the + :paramref:`_schema.Index.unique` parameter set to ``True`` + is generated. See the documentation for + :paramref:`_schema.Column.index` for additional detail. + + Using this flag is equivalent to making use of the + :class:`_schema.UniqueConstraint` construct explicitly at the + level of the :class:`_schema.Table` construct itself:: + + Table( + "some_table", + metadata, + Column("x", Integer), + UniqueConstraint("x") + ) + + The :paramref:`_schema.UniqueConstraint.name` parameter + of the unique constraint object is left at its default value + of ``None``; in the absence of a :ref:`naming convention <constraint_naming_conventions>` + for the enclosing :class:`_schema.MetaData`, the UNIQUE CONSTRAINT + construct will be emitted as unnamed, which typically invokes + a database-specific naming convention to take place. + + As this flag is intended only as a convenience for the common case + of adding a single-column, default configured unique constraint to a table + definition, explicit use of the :class:`_schema.UniqueConstraint` construct + should be preferred for most use cases, including composite constraints + that encompass more than one column, backend-specific index configuration options, and + constraints that use a specific name. + + .. note:: the :attr:`_schema.Column.unique` attribute on + :class:`_schema.Column` + **does not indicate** if this column has a unique constraint or + not, only if this flag was explicitly set here. To view + indexes and unique constraints that may involve this column, + view the + :attr:`_schema.Table.indexes` and/or + :attr:`_schema.Table.constraints` collections or use + :meth:`_reflection.Inspector.get_indexes` and/or + :meth:`_reflection.Inspector.get_unique_constraints` + + .. seealso:: + + :ref:`schema_unique_constraint` + + :ref:`constraint_naming_conventions` + + :paramref:`_schema.Column.index` + + :param system: When ``True``, indicates this is a "system" column, + that is a column which is automatically made available by the + database, and should not be included in the columns list for a + ``CREATE TABLE`` statement. + + For more elaborate scenarios where columns should be + conditionally rendered differently on different backends, + consider custom compilation rules for :class:`.CreateColumn`. + + :param comment: Optional string that will render an SQL comment on + table creation. + + .. versionadded:: 1.2 Added the + :paramref:`_schema.Column.comment` + parameter to :class:`_schema.Column`. + + :param insert_sentinel: Marks this :class:`_schema.Column` as an + :term:`insert sentinel` used for optimizing the performance of the + :term:`insertmanyvalues` feature for tables that don't + otherwise have qualifying primary key configurations. + + .. versionadded:: 2.0.10 + + .. seealso:: + + :func:`_schema.insert_sentinel` - all in one helper for declaring + sentinel columns + + :ref:`engine_insertmanyvalues` + + :ref:`engine_insertmanyvalues_sentinel_columns` + + + """ # noqa: E501, RST201, RST202 + + l_args = [__name_pos, __type_pos] + list(args) + del args + + if l_args: + if isinstance(l_args[0], str): + if name is not None: + raise exc.ArgumentError( + "May not pass name positionally and as a keyword." + ) + name = l_args.pop(0) # type: ignore + elif l_args[0] is None: + l_args.pop(0) + if l_args: + coltype = l_args[0] + + if hasattr(coltype, "_sqla_type"): + if type_ is not None: + raise exc.ArgumentError( + "May not pass type_ positionally and as a keyword." + ) + type_ = l_args.pop(0) # type: ignore + elif l_args[0] is None: + l_args.pop(0) + + if name is not None: + name = quoted_name(name, quote) + elif quote is not None: + raise exc.ArgumentError( + "Explicit 'name' is required when sending 'quote' argument" + ) + + # name = None is expected to be an interim state + # note this use case is legacy now that ORM declarative has a + # dedicated "column" construct local to the ORM + super().__init__(name, type_) # type: ignore + + self.key = key if key is not None else name # type: ignore + self.primary_key = primary_key + self._insert_sentinel = insert_sentinel + self._omit_from_statements = _omit_from_statements + self._user_defined_nullable = udn = nullable + if udn is not NULL_UNSPECIFIED: + self.nullable = udn + else: + self.nullable = not primary_key + + # these default to None because .index and .unique is *not* + # an informational flag about Column - there can still be an + # Index or UniqueConstraint referring to this Column. + self.index = index + self.unique = unique + + self.system = system + self.doc = doc + self.autoincrement: _AutoIncrementType = autoincrement + self.constraints = set() + self.foreign_keys = set() + self.comment = comment + self.computed = None + self.identity = None + + # check if this Column is proxying another column + + if _proxies is not None: + self._proxies = _proxies + else: + # otherwise, add DDL-related events + self._set_type(self.type) + + if default is not None: + if not isinstance(default, (ColumnDefault, Sequence)): + default = ColumnDefault(default) + + self.default = default + l_args.append(default) + else: + self.default = None + + if onupdate is not None: + if not isinstance(onupdate, (ColumnDefault, Sequence)): + onupdate = ColumnDefault(onupdate, for_update=True) + + self.onupdate = onupdate + l_args.append(onupdate) + else: + self.onupdate = None + + if server_default is not None: + if isinstance(server_default, FetchedValue): + server_default = server_default._as_for_update(False) + l_args.append(server_default) + else: + server_default = DefaultClause(server_default) + l_args.append(server_default) + self.server_default = server_default + + if server_onupdate is not None: + if isinstance(server_onupdate, FetchedValue): + server_onupdate = server_onupdate._as_for_update(True) + l_args.append(server_onupdate) + else: + server_onupdate = DefaultClause( + server_onupdate, for_update=True + ) + l_args.append(server_onupdate) + self.server_onupdate = server_onupdate + + self._init_items(*cast(_typing_Sequence[SchemaItem], l_args)) + + util.set_creation_order(self) + + if info is not None: + self.info = info + + self._extra_kwargs(**dialect_kwargs) + + table: Table + + constraints: Set[Constraint] + + foreign_keys: Set[ForeignKey] + """A collection of all :class:`_schema.ForeignKey` marker objects + associated with this :class:`_schema.Column`. + + Each object is a member of a :class:`_schema.Table`-wide + :class:`_schema.ForeignKeyConstraint`. + + .. seealso:: + + :attr:`_schema.Table.foreign_keys` + + """ + + index: Optional[bool] + """The value of the :paramref:`_schema.Column.index` parameter. + + Does not indicate if this :class:`_schema.Column` is actually indexed + or not; use :attr:`_schema.Table.indexes`. + + .. seealso:: + + :attr:`_schema.Table.indexes` + """ + + unique: Optional[bool] + """The value of the :paramref:`_schema.Column.unique` parameter. + + Does not indicate if this :class:`_schema.Column` is actually subject to + a unique constraint or not; use :attr:`_schema.Table.indexes` and + :attr:`_schema.Table.constraints`. + + .. seealso:: + + :attr:`_schema.Table.indexes` + + :attr:`_schema.Table.constraints`. + + """ + + computed: Optional[Computed] + + identity: Optional[Identity] + + def _set_type(self, type_: TypeEngine[Any]) -> None: + assert self.type._isnull or type_ is self.type + + self.type = type_ + if isinstance(self.type, SchemaEventTarget): + self.type._set_parent_with_dispatch(self) + for impl in self.type._variant_mapping.values(): + if isinstance(impl, SchemaEventTarget): + impl._set_parent_with_dispatch(self) + + @HasMemoized.memoized_attribute + def _default_description_tuple(self) -> _DefaultDescriptionTuple: + """used by default.py -> _process_execute_defaults()""" + + return _DefaultDescriptionTuple._from_column_default(self.default) + + @HasMemoized.memoized_attribute + def _onupdate_description_tuple(self) -> _DefaultDescriptionTuple: + """used by default.py -> _process_execute_defaults()""" + return _DefaultDescriptionTuple._from_column_default(self.onupdate) + + @util.memoized_property + def _gen_static_annotations_cache_key(self) -> bool: # type: ignore + """special attribute used by cache key gen, if true, we will + use a static cache key for the annotations dictionary, else we + will generate a new cache key for annotations each time. + + Added for #8790 + + """ + return self.table is not None and self.table._is_table + + def _extra_kwargs(self, **kwargs: Any) -> None: + self._validate_dialect_kwargs(kwargs) + + def __str__(self) -> str: + if self.name is None: + return "(no name)" + elif self.table is not None: + if self.table.named_with_column: + return self.table.description + "." + self.description + else: + return self.description + else: + return self.description + + def references(self, column: Column[Any]) -> bool: + """Return True if this Column references the given column via foreign + key.""" + + for fk in self.foreign_keys: + if fk.column.proxy_set.intersection(column.proxy_set): + return True + else: + return False + + def append_foreign_key(self, fk: ForeignKey) -> None: + fk._set_parent_with_dispatch(self) + + def __repr__(self) -> str: + kwarg = [] + if self.key != self.name: + kwarg.append("key") + if self.primary_key: + kwarg.append("primary_key") + if not self.nullable: + kwarg.append("nullable") + if self.onupdate: + kwarg.append("onupdate") + if self.default: + kwarg.append("default") + if self.server_default: + kwarg.append("server_default") + if self.comment: + kwarg.append("comment") + return "Column(%s)" % ", ".join( + [repr(self.name)] + + [repr(self.type)] + + [repr(x) for x in self.foreign_keys if x is not None] + + [repr(x) for x in self.constraints] + + [ + ( + self.table is not None + and "table=<%s>" % self.table.description + or "table=None" + ) + ] + + ["%s=%s" % (k, repr(getattr(self, k))) for k in kwarg] + ) + + def _set_parent( # type: ignore[override] + self, + parent: SchemaEventTarget, + *, + all_names: Dict[str, Column[Any]], + allow_replacements: bool, + **kw: Any, + ) -> None: + table = parent + assert isinstance(table, Table) + if not self.name: + raise exc.ArgumentError( + "Column must be constructed with a non-blank name or " + "assign a non-blank .name before adding to a Table." + ) + + self._reset_memoizations() + + if self.key is None: + self.key = self.name + + existing = getattr(self, "table", None) + if existing is not None and existing is not table: + raise exc.ArgumentError( + f"Column object '{self.key}' already " + f"assigned to Table '{existing.description}'" + ) + + extra_remove = None + existing_col = None + conflicts_on = "" + + if self.key in table._columns: + existing_col = table._columns[self.key] + if self.key == self.name: + conflicts_on = "name" + else: + conflicts_on = "key" + elif self.name in all_names: + existing_col = all_names[self.name] + extra_remove = {existing_col} + conflicts_on = "name" + + if existing_col is not None: + if existing_col is not self: + if not allow_replacements: + raise exc.DuplicateColumnError( + f"A column with {conflicts_on} " + f"""'{ + self.key if conflicts_on == 'key' else self.name + }' """ + f"is already present in table '{table.name}'." + ) + for fk in existing_col.foreign_keys: + table.foreign_keys.remove(fk) + if fk.constraint in table.constraints: + # this might have been removed + # already, if it's a composite constraint + # and more than one col being replaced + table.constraints.remove(fk.constraint) + + if extra_remove and existing_col is not None and self.key == self.name: + util.warn( + f'Column with user-specified key "{existing_col.key}" is ' + "being replaced with " + f'plain named column "{self.name}", ' + f'key "{existing_col.key}" is being removed. If this is a ' + "reflection operation, specify autoload_replace=False to " + "prevent this replacement." + ) + table._columns.replace(self, extra_remove=extra_remove) + all_names[self.name] = self + self.table = table + + if self._insert_sentinel: + if self.table._sentinel_column is not None: + raise exc.ArgumentError( + "a Table may have only one explicit sentinel column" + ) + self.table._sentinel_column = self + + if self.primary_key: + table.primary_key._replace(self) + elif self.key in table.primary_key: + raise exc.ArgumentError( + f"Trying to redefine primary-key column '{self.key}' as a " + f"non-primary-key column on table '{table.fullname}'" + ) + + if self.index: + if isinstance(self.index, str): + raise exc.ArgumentError( + "The 'index' keyword argument on Column is boolean only. " + "To create indexes with a specific name, create an " + "explicit Index object external to the Table." + ) + table.append_constraint( + Index( + None, self.key, unique=bool(self.unique), _column_flag=True + ) + ) + + elif self.unique: + if isinstance(self.unique, str): + raise exc.ArgumentError( + "The 'unique' keyword argument on Column is boolean " + "only. To create unique constraints or indexes with a " + "specific name, append an explicit UniqueConstraint to " + "the Table's list of elements, or create an explicit " + "Index object external to the Table." + ) + table.append_constraint( + UniqueConstraint(self.key, _column_flag=True) + ) + + self._setup_on_memoized_fks(lambda fk: fk._set_remote_table(table)) + + if self.identity and ( + isinstance(self.default, Sequence) + or isinstance(self.onupdate, Sequence) + ): + raise exc.ArgumentError( + "An column cannot specify both Identity and Sequence." + ) + + def _setup_on_memoized_fks(self, fn: Callable[..., Any]) -> None: + fk_keys = [ + ((self.table.key, self.key), False), + ((self.table.key, self.name), True), + ] + for fk_key, link_to_name in fk_keys: + if fk_key in self.table.metadata._fk_memos: + for fk in self.table.metadata._fk_memos[fk_key]: + if fk.link_to_name is link_to_name: + fn(fk) + + def _on_table_attach(self, fn: Callable[..., Any]) -> None: + if self.table is not None: + fn(self, self.table) + else: + event.listen(self, "after_parent_attach", fn) + + @util.deprecated( + "1.4", + "The :meth:`_schema.Column.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy(self, **kw: Any) -> Column[Any]: + return self._copy(**kw) + + def _copy(self, **kw: Any) -> Column[Any]: + """Create a copy of this ``Column``, uninitialized. + + This is used in :meth:`_schema.Table.to_metadata` and by the ORM. + + """ + + # Constraint objects plus non-constraint-bound ForeignKey objects + args: List[SchemaItem] = [ + c._copy(**kw) for c in self.constraints if not c._type_bound + ] + [c._copy(**kw) for c in self.foreign_keys if not c.constraint] + + # ticket #5276 + column_kwargs = {} + for dialect_name in self.dialect_options: + dialect_options = self.dialect_options[dialect_name]._non_defaults + for ( + dialect_option_key, + dialect_option_value, + ) in dialect_options.items(): + column_kwargs[dialect_name + "_" + dialect_option_key] = ( + dialect_option_value + ) + + server_default = self.server_default + server_onupdate = self.server_onupdate + if isinstance(server_default, (Computed, Identity)): + # TODO: likely should be copied in all cases + args.append(server_default._copy(**kw)) + server_default = server_onupdate = None + + type_ = self.type + if isinstance(type_, SchemaEventTarget): + type_ = type_.copy(**kw) + + # TODO: DefaultGenerator is not copied here! it's just used again + # with _set_parent() pointing to the old column. see the new + # use of _copy() in the new _merge() method + + c = self._constructor( + name=self.name, + type_=type_, + key=self.key, + primary_key=self.primary_key, + unique=self.unique, + system=self.system, + # quote=self.quote, # disabled 2013-08-27 (commit 031ef080) + index=self.index, + autoincrement=self.autoincrement, + default=self.default, + server_default=server_default, + onupdate=self.onupdate, + server_onupdate=server_onupdate, + doc=self.doc, + comment=self.comment, + _omit_from_statements=self._omit_from_statements, + insert_sentinel=self._insert_sentinel, + *args, + **column_kwargs, + ) + + # copy the state of "nullable" exactly, to accommodate for + # ORM flipping the .nullable flag directly + c.nullable = self.nullable + c._user_defined_nullable = self._user_defined_nullable + + return self._schema_item_copy(c) + + def _merge(self, other: Column[Any]) -> None: + """merge the elements of another column into this one. + + this is used by ORM pep-593 merge and will likely need a lot + of fixes. + + + """ + + if self.primary_key: + other.primary_key = True + + if self.autoincrement != "auto" and other.autoincrement == "auto": + other.autoincrement = self.autoincrement + + if self.system: + other.system = self.system + + if self.info: + other.info.update(self.info) + + type_ = self.type + if not type_._isnull and other.type._isnull: + if isinstance(type_, SchemaEventTarget): + type_ = type_.copy() + + other.type = type_ + + if isinstance(type_, SchemaEventTarget): + type_._set_parent_with_dispatch(other) + + for impl in type_._variant_mapping.values(): + if isinstance(impl, SchemaEventTarget): + impl._set_parent_with_dispatch(other) + + if ( + self._user_defined_nullable is not NULL_UNSPECIFIED + and other._user_defined_nullable is NULL_UNSPECIFIED + ): + other.nullable = self.nullable + other._user_defined_nullable = self._user_defined_nullable + + if self.default is not None and other.default is None: + new_default = self.default._copy() + new_default._set_parent(other) + + if self.server_default and other.server_default is None: + new_server_default = self.server_default + if isinstance(new_server_default, FetchedValue): + new_server_default = new_server_default._copy() + new_server_default._set_parent(other) + else: + other.server_default = new_server_default + + if self.server_onupdate and other.server_onupdate is None: + new_server_onupdate = self.server_onupdate + new_server_onupdate = new_server_onupdate._copy() + new_server_onupdate._set_parent(other) + + if self.onupdate and other.onupdate is None: + new_onupdate = self.onupdate._copy() + new_onupdate._set_parent(other) + + if self.index in (True, False) and other.index is None: + other.index = self.index + + if self.unique in (True, False) and other.unique is None: + other.unique = self.unique + + if self.doc and other.doc is None: + other.doc = self.doc + + if self.comment and other.comment is None: + other.comment = self.comment + + for const in self.constraints: + if not const._type_bound: + new_const = const._copy() + new_const._set_parent(other) + + for fk in self.foreign_keys: + if not fk.constraint: + new_fk = fk._copy() + new_fk._set_parent(other) + + def _make_proxy( + self, + selectable: FromClause, + name: Optional[str] = None, + key: Optional[str] = None, + name_is_truncatable: bool = False, + compound_select_cols: Optional[ + _typing_Sequence[ColumnElement[Any]] + ] = None, + **kw: Any, + ) -> Tuple[str, ColumnClause[_T]]: + """Create a *proxy* for this column. + + This is a copy of this ``Column`` referenced by a different parent + (such as an alias or select statement). The column should + be used only in select scenarios, as its full DDL/default + information is not transferred. + + """ + + fk = [ + ForeignKey( + col if col is not None else f._colspec, + _unresolvable=col is None, + _constraint=f.constraint, + ) + for f, col in [ + (fk, fk._resolve_column(raiseerr=False)) + for fk in self.foreign_keys + ] + ] + + if name is None and self.name is None: + raise exc.InvalidRequestError( + "Cannot initialize a sub-selectable" + " with this Column object until its 'name' has " + "been assigned." + ) + try: + c = self._constructor( + ( + coercions.expect( + roles.TruncatedLabelRole, name if name else self.name + ) + if name_is_truncatable + else (name or self.name) + ), + self.type, + # this may actually be ._proxy_key when the key is incoming + key=key if key else name if name else self.key, + primary_key=self.primary_key, + nullable=self.nullable, + _proxies=( + list(compound_select_cols) + if compound_select_cols + else [self] + ), + *fk, + ) + except TypeError as err: + raise TypeError( + "Could not create a copy of this %r object. " + "Ensure the class includes a _constructor() " + "attribute or method which accepts the " + "standard Column constructor arguments, or " + "references the Column class itself." % self.__class__ + ) from err + + c.table = selectable + c._propagate_attrs = selectable._propagate_attrs + if selectable._is_clone_of is not None: + c._is_clone_of = selectable._is_clone_of.columns.get(c.key) + if self.primary_key: + selectable.primary_key.add(c) # type: ignore + if fk: + selectable.foreign_keys.update(fk) # type: ignore + return c.key, c + + +def insert_sentinel( + name: Optional[str] = None, + type_: Optional[_TypeEngineArgument[_T]] = None, + *, + default: Optional[Any] = None, + omit_from_statements: bool = True, +) -> Column[Any]: + """Provides a surrogate :class:`_schema.Column` that will act as a + dedicated insert :term:`sentinel` column, allowing efficient bulk + inserts with deterministic RETURNING sorting for tables that + don't otherwise have qualifying primary key configurations. + + Adding this column to a :class:`.Table` object requires that a + corresponding database table actually has this column present, so if adding + it to an existing model, existing database tables would need to be migrated + (e.g. using ALTER TABLE or similar) to include this column. + + For background on how this object is used, see the section + :ref:`engine_insertmanyvalues_sentinel_columns` as part of the + section :ref:`engine_insertmanyvalues`. + + The :class:`_schema.Column` returned will be a nullable integer column by + default and make use of a sentinel-specific default generator used only in + "insertmanyvalues" operations. + + .. seealso:: + + :func:`_orm.orm_insert_sentinel` + + :paramref:`_schema.Column.insert_sentinel` + + :ref:`engine_insertmanyvalues` + + :ref:`engine_insertmanyvalues_sentinel_columns` + + + .. versionadded:: 2.0.10 + + """ + return Column( + name=name, + type_=type_api.INTEGERTYPE if type_ is None else type_, + default=( + default if default is not None else _InsertSentinelColumnDefault() + ), + _omit_from_statements=omit_from_statements, + insert_sentinel=True, + ) + + +class ForeignKey(DialectKWArgs, SchemaItem): + """Defines a dependency between two columns. + + ``ForeignKey`` is specified as an argument to a :class:`_schema.Column` + object, + e.g.:: + + t = Table("remote_table", metadata, + Column("remote_id", ForeignKey("main_table.id")) + ) + + Note that ``ForeignKey`` is only a marker object that defines + a dependency between two columns. The actual constraint + is in all cases represented by the :class:`_schema.ForeignKeyConstraint` + object. This object will be generated automatically when + a ``ForeignKey`` is associated with a :class:`_schema.Column` which + in turn is associated with a :class:`_schema.Table`. Conversely, + when :class:`_schema.ForeignKeyConstraint` is applied to a + :class:`_schema.Table`, + ``ForeignKey`` markers are automatically generated to be + present on each associated :class:`_schema.Column`, which are also + associated with the constraint object. + + Note that you cannot define a "composite" foreign key constraint, + that is a constraint between a grouping of multiple parent/child + columns, using ``ForeignKey`` objects. To define this grouping, + the :class:`_schema.ForeignKeyConstraint` object must be used, and applied + to the :class:`_schema.Table`. The associated ``ForeignKey`` objects + are created automatically. + + The ``ForeignKey`` objects associated with an individual + :class:`_schema.Column` + object are available in the `foreign_keys` collection + of that column. + + Further examples of foreign key configuration are in + :ref:`metadata_foreignkeys`. + + """ + + __visit_name__ = "foreign_key" + + parent: Column[Any] + + _table_column: Optional[Column[Any]] + + def __init__( + self, + column: _DDLColumnArgument, + _constraint: Optional[ForeignKeyConstraint] = None, + use_alter: bool = False, + name: _ConstraintNameArgument = None, + onupdate: Optional[str] = None, + ondelete: Optional[str] = None, + deferrable: Optional[bool] = None, + initially: Optional[str] = None, + link_to_name: bool = False, + match: Optional[str] = None, + info: Optional[_InfoType] = None, + comment: Optional[str] = None, + _unresolvable: bool = False, + **dialect_kw: Any, + ): + r""" + Construct a column-level FOREIGN KEY. + + The :class:`_schema.ForeignKey` object when constructed generates a + :class:`_schema.ForeignKeyConstraint` + which is associated with the parent + :class:`_schema.Table` object's collection of constraints. + + :param column: A single target column for the key relationship. A + :class:`_schema.Column` object or a column name as a string: + ``tablename.columnkey`` or ``schema.tablename.columnkey``. + ``columnkey`` is the ``key`` which has been assigned to the column + (defaults to the column name itself), unless ``link_to_name`` is + ``True`` in which case the rendered name of the column is used. + + :param name: Optional string. An in-database name for the key if + `constraint` is not provided. + + :param onupdate: Optional string. If set, emit ON UPDATE <value> when + issuing DDL for this constraint. Typical values include CASCADE, + DELETE and RESTRICT. + + :param ondelete: Optional string. If set, emit ON DELETE <value> when + issuing DDL for this constraint. Typical values include CASCADE, + DELETE and RESTRICT. + + :param deferrable: Optional bool. If set, emit DEFERRABLE or NOT + DEFERRABLE when issuing DDL for this constraint. + + :param initially: Optional string. If set, emit INITIALLY <value> when + issuing DDL for this constraint. + + :param link_to_name: if True, the string name given in ``column`` is + the rendered name of the referenced column, not its locally + assigned ``key``. + + :param use_alter: passed to the underlying + :class:`_schema.ForeignKeyConstraint` + to indicate the constraint should + be generated/dropped externally from the CREATE TABLE/ DROP TABLE + statement. See :paramref:`_schema.ForeignKeyConstraint.use_alter` + for further description. + + .. seealso:: + + :paramref:`_schema.ForeignKeyConstraint.use_alter` + + :ref:`use_alter` + + :param match: Optional string. If set, emit MATCH <value> when issuing + DDL for this constraint. Typical values include SIMPLE, PARTIAL + and FULL. + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + :param comment: Optional string that will render an SQL comment on + foreign key constraint creation. + + .. versionadded:: 2.0 + + :param \**dialect_kw: Additional keyword arguments are dialect + specific, and passed in the form ``<dialectname>_<argname>``. The + arguments are ultimately handled by a corresponding + :class:`_schema.ForeignKeyConstraint`. + See the documentation regarding + an individual dialect at :ref:`dialect_toplevel` for detail on + documented arguments. + + """ + + self._colspec = coercions.expect(roles.DDLReferredColumnRole, column) + self._unresolvable = _unresolvable + + if isinstance(self._colspec, str): + self._table_column = None + else: + self._table_column = self._colspec + + if not isinstance( + self._table_column.table, (type(None), TableClause) + ): + raise exc.ArgumentError( + "ForeignKey received Column not bound " + "to a Table, got: %r" % self._table_column.table + ) + + # the linked ForeignKeyConstraint. + # ForeignKey will create this when parent Column + # is attached to a Table, *or* ForeignKeyConstraint + # object passes itself in when creating ForeignKey + # markers. + self.constraint = _constraint + + # .parent is not Optional under normal use + self.parent = None # type: ignore + + self.use_alter = use_alter + self.name = name + self.onupdate = onupdate + self.ondelete = ondelete + self.deferrable = deferrable + self.initially = initially + self.link_to_name = link_to_name + self.match = match + self.comment = comment + if info: + self.info = info + self._unvalidated_dialect_kw = dialect_kw + + def __repr__(self) -> str: + return "ForeignKey(%r)" % self._get_colspec() + + @util.deprecated( + "1.4", + "The :meth:`_schema.ForeignKey.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy(self, *, schema: Optional[str] = None, **kw: Any) -> ForeignKey: + return self._copy(schema=schema, **kw) + + def _copy(self, *, schema: Optional[str] = None, **kw: Any) -> ForeignKey: + """Produce a copy of this :class:`_schema.ForeignKey` object. + + The new :class:`_schema.ForeignKey` will not be bound + to any :class:`_schema.Column`. + + This method is usually used by the internal + copy procedures of :class:`_schema.Column`, :class:`_schema.Table`, + and :class:`_schema.MetaData`. + + :param schema: The returned :class:`_schema.ForeignKey` will + reference the original table and column name, qualified + by the given string schema name. + + """ + fk = ForeignKey( + self._get_colspec(schema=schema), + use_alter=self.use_alter, + name=self.name, + onupdate=self.onupdate, + ondelete=self.ondelete, + deferrable=self.deferrable, + initially=self.initially, + link_to_name=self.link_to_name, + match=self.match, + comment=self.comment, + **self._unvalidated_dialect_kw, + ) + return self._schema_item_copy(fk) + + def _get_colspec( + self, + schema: Optional[ + Union[ + str, + Literal[SchemaConst.RETAIN_SCHEMA, SchemaConst.BLANK_SCHEMA], + ] + ] = None, + table_name: Optional[str] = None, + _is_copy: bool = False, + ) -> str: + """Return a string based 'column specification' for this + :class:`_schema.ForeignKey`. + + This is usually the equivalent of the string-based "tablename.colname" + argument first passed to the object's constructor. + + """ + if schema not in (None, RETAIN_SCHEMA): + _schema, tname, colname = self._column_tokens + if table_name is not None: + tname = table_name + if schema is BLANK_SCHEMA: + return "%s.%s" % (tname, colname) + else: + return "%s.%s.%s" % (schema, tname, colname) + elif table_name: + schema, tname, colname = self._column_tokens + if schema: + return "%s.%s.%s" % (schema, table_name, colname) + else: + return "%s.%s" % (table_name, colname) + elif self._table_column is not None: + if self._table_column.table is None: + if _is_copy: + raise exc.InvalidRequestError( + f"Can't copy ForeignKey object which refers to " + f"non-table bound Column {self._table_column!r}" + ) + else: + return self._table_column.key + return "%s.%s" % ( + self._table_column.table.fullname, + self._table_column.key, + ) + else: + assert isinstance(self._colspec, str) + return self._colspec + + @property + def _referred_schema(self) -> Optional[str]: + return self._column_tokens[0] + + def _table_key(self) -> Any: + if self._table_column is not None: + if self._table_column.table is None: + return None + else: + return self._table_column.table.key + else: + schema, tname, colname = self._column_tokens + return _get_table_key(tname, schema) + + target_fullname = property(_get_colspec) + + def references(self, table: Table) -> bool: + """Return True if the given :class:`_schema.Table` + is referenced by this + :class:`_schema.ForeignKey`.""" + + return table.corresponding_column(self.column) is not None + + def get_referent(self, table: FromClause) -> Optional[Column[Any]]: + """Return the :class:`_schema.Column` in the given + :class:`_schema.Table` (or any :class:`.FromClause`) + referenced by this :class:`_schema.ForeignKey`. + + Returns None if this :class:`_schema.ForeignKey` + does not reference the given + :class:`_schema.Table`. + + """ + # our column is a Column, and any subquery etc. proxying us + # would be doing so via another Column, so that's what would + # be returned here + return table.columns.corresponding_column(self.column) # type: ignore + + @util.memoized_property + def _column_tokens(self) -> Tuple[Optional[str], str, Optional[str]]: + """parse a string-based _colspec into its component parts.""" + + m = self._get_colspec().split(".") + if m is None: + raise exc.ArgumentError( + f"Invalid foreign key column specification: {self._colspec}" + ) + if len(m) == 1: + tname = m.pop() + colname = None + else: + colname = m.pop() + tname = m.pop() + + # A FK between column 'bar' and table 'foo' can be + # specified as 'foo', 'foo.bar', 'dbo.foo.bar', + # 'otherdb.dbo.foo.bar'. Once we have the column name and + # the table name, treat everything else as the schema + # name. Some databases (e.g. Sybase) support + # inter-database foreign keys. See tickets#1341 and -- + # indirectly related -- Ticket #594. This assumes that '.' + # will never appear *within* any component of the FK. + + if len(m) > 0: + schema = ".".join(m) + else: + schema = None + return schema, tname, colname + + def _resolve_col_tokens(self) -> Tuple[Table, str, Optional[str]]: + if self.parent is None: + raise exc.InvalidRequestError( + "this ForeignKey object does not yet have a " + "parent Column associated with it." + ) + + elif self.parent.table is None: + raise exc.InvalidRequestError( + "this ForeignKey's parent column is not yet associated " + "with a Table." + ) + + parenttable = self.parent.table + + if self._unresolvable: + schema, tname, colname = self._column_tokens + tablekey = _get_table_key(tname, schema) + return parenttable, tablekey, colname + + # assertion + # basically Column._make_proxy() sends the actual + # target Column to the ForeignKey object, so the + # string resolution here is never called. + for c in self.parent.base_columns: + if isinstance(c, Column): + assert c.table is parenttable + break + else: + assert False + ###################### + + schema, tname, colname = self._column_tokens + + if schema is None and parenttable.metadata.schema is not None: + schema = parenttable.metadata.schema + + tablekey = _get_table_key(tname, schema) + return parenttable, tablekey, colname + + def _link_to_col_by_colstring( + self, parenttable: Table, table: Table, colname: Optional[str] + ) -> Column[Any]: + _column = None + if colname is None: + # colname is None in the case that ForeignKey argument + # was specified as table name only, in which case we + # match the column name to the same column on the + # parent. + # this use case wasn't working in later 1.x series + # as it had no test coverage; fixed in 2.0 + parent = self.parent + assert parent is not None + key = parent.key + _column = table.c.get(key, None) + elif self.link_to_name: + key = colname + for c in table.c: + if c.name == colname: + _column = c + else: + key = colname + _column = table.c.get(colname, None) + + if _column is None: + raise exc.NoReferencedColumnError( + "Could not initialize target column " + f"for ForeignKey '{self._colspec}' " + f"on table '{parenttable.name}': " + f"table '{table.name}' has no column named '{key}'", + table.name, + key, + ) + + return _column + + def _set_target_column(self, column: Column[Any]) -> None: + assert self.parent is not None + + # propagate TypeEngine to parent if it didn't have one + if self.parent.type._isnull: + self.parent.type = column.type + + # super-edgy case, if other FKs point to our column, + # they'd get the type propagated out also. + + def set_type(fk: ForeignKey) -> None: + if fk.parent.type._isnull: + fk.parent.type = column.type + + self.parent._setup_on_memoized_fks(set_type) + + self.column = column # type: ignore + + @util.ro_memoized_property + def column(self) -> Column[Any]: + """Return the target :class:`_schema.Column` referenced by this + :class:`_schema.ForeignKey`. + + If no target column has been established, an exception + is raised. + + """ + + return self._resolve_column() + + @overload + def _resolve_column( + self, *, raiseerr: Literal[True] = ... + ) -> Column[Any]: ... + + @overload + def _resolve_column( + self, *, raiseerr: bool = ... + ) -> Optional[Column[Any]]: ... + + def _resolve_column( + self, *, raiseerr: bool = True + ) -> Optional[Column[Any]]: + _column: Column[Any] + + if isinstance(self._colspec, str): + parenttable, tablekey, colname = self._resolve_col_tokens() + + if self._unresolvable or tablekey not in parenttable.metadata: + if not raiseerr: + return None + raise exc.NoReferencedTableError( + f"Foreign key associated with column " + f"'{self.parent}' could not find " + f"table '{tablekey}' with which to generate a " + f"foreign key to target column '{colname}'", + tablekey, + ) + elif parenttable.key not in parenttable.metadata: + if not raiseerr: + return None + raise exc.InvalidRequestError( + f"Table {parenttable} is no longer associated with its " + "parent MetaData" + ) + else: + table = parenttable.metadata.tables[tablekey] + return self._link_to_col_by_colstring( + parenttable, table, colname + ) + + elif hasattr(self._colspec, "__clause_element__"): + _column = self._colspec.__clause_element__() + return _column + else: + _column = self._colspec + return _column + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + assert isinstance(parent, Column) + + if self.parent is not None and self.parent is not parent: + raise exc.InvalidRequestError( + "This ForeignKey already has a parent !" + ) + self.parent = parent + self.parent.foreign_keys.add(self) + self.parent._on_table_attach(self._set_table) + + def _set_remote_table(self, table: Table) -> None: + parenttable, _, colname = self._resolve_col_tokens() + _column = self._link_to_col_by_colstring(parenttable, table, colname) + self._set_target_column(_column) + assert self.constraint is not None + self.constraint._validate_dest_table(table) + + def _remove_from_metadata(self, metadata: MetaData) -> None: + parenttable, table_key, colname = self._resolve_col_tokens() + fk_key = (table_key, colname) + + if self in metadata._fk_memos[fk_key]: + # TODO: no test coverage for self not in memos + metadata._fk_memos[fk_key].remove(self) + + def _set_table(self, column: Column[Any], table: Table) -> None: + # standalone ForeignKey - create ForeignKeyConstraint + # on the hosting Table when attached to the Table. + assert isinstance(table, Table) + if self.constraint is None: + self.constraint = ForeignKeyConstraint( + [], + [], + use_alter=self.use_alter, + name=self.name, + onupdate=self.onupdate, + ondelete=self.ondelete, + deferrable=self.deferrable, + initially=self.initially, + match=self.match, + comment=self.comment, + **self._unvalidated_dialect_kw, + ) + self.constraint._append_element(column, self) + self.constraint._set_parent_with_dispatch(table) + table.foreign_keys.add(self) + # set up remote ".column" attribute, or a note to pick it + # up when the other Table/Column shows up + if isinstance(self._colspec, str): + parenttable, table_key, colname = self._resolve_col_tokens() + fk_key = (table_key, colname) + if table_key in parenttable.metadata.tables: + table = parenttable.metadata.tables[table_key] + try: + _column = self._link_to_col_by_colstring( + parenttable, table, colname + ) + except exc.NoReferencedColumnError: + # this is OK, we'll try later + pass + else: + self._set_target_column(_column) + + parenttable.metadata._fk_memos[fk_key].append(self) + elif hasattr(self._colspec, "__clause_element__"): + _column = self._colspec.__clause_element__() + self._set_target_column(_column) + else: + _column = self._colspec + self._set_target_column(_column) + + +if TYPE_CHECKING: + + def default_is_sequence( + obj: Optional[DefaultGenerator], + ) -> TypeGuard[Sequence]: ... + + def default_is_clause_element( + obj: Optional[DefaultGenerator], + ) -> TypeGuard[ColumnElementColumnDefault]: ... + + def default_is_scalar( + obj: Optional[DefaultGenerator], + ) -> TypeGuard[ScalarElementColumnDefault]: ... + +else: + default_is_sequence = operator.attrgetter("is_sequence") + + default_is_clause_element = operator.attrgetter("is_clause_element") + + default_is_scalar = operator.attrgetter("is_scalar") + + +class DefaultGenerator(Executable, SchemaItem): + """Base class for column *default* values. + + This object is only present on column.default or column.onupdate. + It's not valid as a server default. + + """ + + __visit_name__ = "default_generator" + + _is_default_generator = True + is_sequence = False + is_identity = False + is_server_default = False + is_clause_element = False + is_callable = False + is_scalar = False + has_arg = False + is_sentinel = False + column: Optional[Column[Any]] + + def __init__(self, for_update: bool = False) -> None: + self.for_update = for_update + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + if TYPE_CHECKING: + assert isinstance(parent, Column) + self.column = parent + if self.for_update: + self.column.onupdate = self + else: + self.column.default = self + + def _copy(self) -> DefaultGenerator: + raise NotImplementedError() + + def _execute_on_connection( + self, + connection: Connection, + distilled_params: _CoreMultiExecuteParams, + execution_options: CoreExecuteOptionsParameter, + ) -> Any: + util.warn_deprecated( + "Using the .execute() method to invoke a " + "DefaultGenerator object is deprecated; please use " + "the .scalar() method.", + "2.0", + ) + return self._execute_on_scalar( + connection, distilled_params, execution_options + ) + + def _execute_on_scalar( + self, + connection: Connection, + distilled_params: _CoreMultiExecuteParams, + execution_options: CoreExecuteOptionsParameter, + ) -> Any: + return connection._execute_default( + self, distilled_params, execution_options + ) + + +class ColumnDefault(DefaultGenerator, ABC): + """A plain default value on a column. + + This could correspond to a constant, a callable function, + or a SQL clause. + + :class:`.ColumnDefault` is generated automatically + whenever the ``default``, ``onupdate`` arguments of + :class:`_schema.Column` are used. A :class:`.ColumnDefault` + can be passed positionally as well. + + For example, the following:: + + Column('foo', Integer, default=50) + + Is equivalent to:: + + Column('foo', Integer, ColumnDefault(50)) + + + """ + + arg: Any + + @overload + def __new__( + cls, arg: Callable[..., Any], for_update: bool = ... + ) -> CallableColumnDefault: ... + + @overload + def __new__( + cls, arg: ColumnElement[Any], for_update: bool = ... + ) -> ColumnElementColumnDefault: ... + + # if I return ScalarElementColumnDefault here, which is what's actually + # returned, mypy complains that + # overloads overlap w/ incompatible return types. + @overload + def __new__(cls, arg: object, for_update: bool = ...) -> ColumnDefault: ... + + def __new__( + cls, arg: Any = None, for_update: bool = False + ) -> ColumnDefault: + """Construct a new :class:`.ColumnDefault`. + + + :param arg: argument representing the default value. + May be one of the following: + + * a plain non-callable Python value, such as a + string, integer, boolean, or other simple type. + The default value will be used as is each time. + * a SQL expression, that is one which derives from + :class:`_expression.ColumnElement`. The SQL expression will + be rendered into the INSERT or UPDATE statement, + or in the case of a primary key column when + RETURNING is not used may be + pre-executed before an INSERT within a SELECT. + * A Python callable. The function will be invoked for each + new row subject to an INSERT or UPDATE. + The callable must accept exactly + zero or one positional arguments. The one-argument form + will receive an instance of the :class:`.ExecutionContext`, + which provides contextual information as to the current + :class:`_engine.Connection` in use as well as the current + statement and parameters. + + """ + + if isinstance(arg, FetchedValue): + raise exc.ArgumentError( + "ColumnDefault may not be a server-side default type." + ) + elif callable(arg): + cls = CallableColumnDefault + elif isinstance(arg, ClauseElement): + cls = ColumnElementColumnDefault + elif arg is not None: + cls = ScalarElementColumnDefault + + return object.__new__(cls) + + def __repr__(self) -> str: + return f"{self.__class__.__name__}({self.arg!r})" + + +class ScalarElementColumnDefault(ColumnDefault): + """default generator for a fixed scalar Python value + + .. versionadded: 2.0 + + """ + + is_scalar = True + has_arg = True + + def __init__(self, arg: Any, for_update: bool = False) -> None: + self.for_update = for_update + self.arg = arg + + def _copy(self) -> ScalarElementColumnDefault: + return ScalarElementColumnDefault( + arg=self.arg, for_update=self.for_update + ) + + +class _InsertSentinelColumnDefault(ColumnDefault): + """Default generator that's specific to the use of a "sentinel" column + when using the insertmanyvalues feature. + + This default is used as part of the :func:`_schema.insert_sentinel` + construct. + + """ + + is_sentinel = True + for_update = False + arg = None + + def __new__(cls) -> _InsertSentinelColumnDefault: + return object.__new__(cls) + + def __init__(self) -> None: + pass + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + col = cast("Column[Any]", parent) + if not col._insert_sentinel: + raise exc.ArgumentError( + "The _InsertSentinelColumnDefault may only be applied to a " + "Column marked as insert_sentinel=True" + ) + elif not col.nullable: + raise exc.ArgumentError( + "The _InsertSentinelColumnDefault may only be applied to a " + "Column that is nullable" + ) + + super()._set_parent(parent, **kw) + + def _copy(self) -> _InsertSentinelColumnDefault: + return _InsertSentinelColumnDefault() + + +_SQLExprDefault = Union["ColumnElement[Any]", "TextClause"] + + +class ColumnElementColumnDefault(ColumnDefault): + """default generator for a SQL expression + + .. versionadded:: 2.0 + + """ + + is_clause_element = True + has_arg = True + arg: _SQLExprDefault + + def __init__( + self, + arg: _SQLExprDefault, + for_update: bool = False, + ) -> None: + self.for_update = for_update + self.arg = arg + + def _copy(self) -> ColumnElementColumnDefault: + return ColumnElementColumnDefault( + arg=self.arg, for_update=self.for_update + ) + + @util.memoized_property + @util.preload_module("sqlalchemy.sql.sqltypes") + def _arg_is_typed(self) -> bool: + sqltypes = util.preloaded.sql_sqltypes + + return not isinstance(self.arg.type, sqltypes.NullType) + + +class _CallableColumnDefaultProtocol(Protocol): + def __call__(self, context: ExecutionContext) -> Any: ... + + +class CallableColumnDefault(ColumnDefault): + """default generator for a callable Python function + + .. versionadded:: 2.0 + + """ + + is_callable = True + arg: _CallableColumnDefaultProtocol + has_arg = True + + def __init__( + self, + arg: Union[_CallableColumnDefaultProtocol, Callable[[], Any]], + for_update: bool = False, + ) -> None: + self.for_update = for_update + self.arg = self._maybe_wrap_callable(arg) + + def _copy(self) -> CallableColumnDefault: + return CallableColumnDefault(arg=self.arg, for_update=self.for_update) + + def _maybe_wrap_callable( + self, fn: Union[_CallableColumnDefaultProtocol, Callable[[], Any]] + ) -> _CallableColumnDefaultProtocol: + """Wrap callables that don't accept a context. + + This is to allow easy compatibility with default callables + that aren't specific to accepting of a context. + + """ + + try: + argspec = util.get_callable_argspec(fn, no_self=True) + except TypeError: + return util.wrap_callable(lambda ctx: fn(), fn) # type: ignore + + defaulted = argspec[3] is not None and len(argspec[3]) or 0 + positionals = len(argspec[0]) - defaulted + + if positionals == 0: + return util.wrap_callable(lambda ctx: fn(), fn) # type: ignore + + elif positionals == 1: + return fn # type: ignore + else: + raise exc.ArgumentError( + "ColumnDefault Python function takes zero or one " + "positional arguments" + ) + + +class IdentityOptions: + """Defines options for a named database sequence or an identity column. + + .. versionadded:: 1.3.18 + + .. seealso:: + + :class:`.Sequence` + + """ + + def __init__( + self, + start: Optional[int] = None, + increment: Optional[int] = None, + minvalue: Optional[int] = None, + maxvalue: Optional[int] = None, + nominvalue: Optional[bool] = None, + nomaxvalue: Optional[bool] = None, + cycle: Optional[bool] = None, + cache: Optional[int] = None, + order: Optional[bool] = None, + ) -> None: + """Construct a :class:`.IdentityOptions` object. + + See the :class:`.Sequence` documentation for a complete description + of the parameters. + + :param start: the starting index of the sequence. + :param increment: the increment value of the sequence. + :param minvalue: the minimum value of the sequence. + :param maxvalue: the maximum value of the sequence. + :param nominvalue: no minimum value of the sequence. + :param nomaxvalue: no maximum value of the sequence. + :param cycle: allows the sequence to wrap around when the maxvalue + or minvalue has been reached. + :param cache: optional integer value; number of future values in the + sequence which are calculated in advance. + :param order: optional boolean value; if ``True``, renders the + ORDER keyword. + + """ + self.start = start + self.increment = increment + self.minvalue = minvalue + self.maxvalue = maxvalue + self.nominvalue = nominvalue + self.nomaxvalue = nomaxvalue + self.cycle = cycle + self.cache = cache + self.order = order + + @property + def _increment_is_negative(self) -> bool: + return self.increment is not None and self.increment < 0 + + +class Sequence(HasSchemaAttr, IdentityOptions, DefaultGenerator): + """Represents a named database sequence. + + The :class:`.Sequence` object represents the name and configurational + parameters of a database sequence. It also represents + a construct that can be "executed" by a SQLAlchemy :class:`_engine.Engine` + or :class:`_engine.Connection`, + rendering the appropriate "next value" function + for the target database and returning a result. + + The :class:`.Sequence` is typically associated with a primary key column:: + + some_table = Table( + 'some_table', metadata, + Column('id', Integer, Sequence('some_table_seq', start=1), + primary_key=True) + ) + + When CREATE TABLE is emitted for the above :class:`_schema.Table`, if the + target platform supports sequences, a CREATE SEQUENCE statement will + be emitted as well. For platforms that don't support sequences, + the :class:`.Sequence` construct is ignored. + + .. seealso:: + + :ref:`defaults_sequences` + + :class:`.CreateSequence` + + :class:`.DropSequence` + + """ + + __visit_name__ = "sequence" + + is_sequence = True + + column: Optional[Column[Any]] + data_type: Optional[TypeEngine[int]] + + def __init__( + self, + name: str, + start: Optional[int] = None, + increment: Optional[int] = None, + minvalue: Optional[int] = None, + maxvalue: Optional[int] = None, + nominvalue: Optional[bool] = None, + nomaxvalue: Optional[bool] = None, + cycle: Optional[bool] = None, + schema: Optional[Union[str, Literal[SchemaConst.BLANK_SCHEMA]]] = None, + cache: Optional[int] = None, + order: Optional[bool] = None, + data_type: Optional[_TypeEngineArgument[int]] = None, + optional: bool = False, + quote: Optional[bool] = None, + metadata: Optional[MetaData] = None, + quote_schema: Optional[bool] = None, + for_update: bool = False, + ) -> None: + """Construct a :class:`.Sequence` object. + + :param name: the name of the sequence. + + :param start: the starting index of the sequence. This value is + used when the CREATE SEQUENCE command is emitted to the database + as the value of the "START WITH" clause. If ``None``, the + clause is omitted, which on most platforms indicates a starting + value of 1. + + .. versionchanged:: 2.0 The :paramref:`.Sequence.start` parameter + is required in order to have DDL emit "START WITH". This is a + reversal of a change made in version 1.4 which would implicitly + render "START WITH 1" if the :paramref:`.Sequence.start` were + not included. See :ref:`change_7211` for more detail. + + :param increment: the increment value of the sequence. This + value is used when the CREATE SEQUENCE command is emitted to + the database as the value of the "INCREMENT BY" clause. If ``None``, + the clause is omitted, which on most platforms indicates an + increment of 1. + :param minvalue: the minimum value of the sequence. This + value is used when the CREATE SEQUENCE command is emitted to + the database as the value of the "MINVALUE" clause. If ``None``, + the clause is omitted, which on most platforms indicates a + minvalue of 1 and -2^63-1 for ascending and descending sequences, + respectively. + + :param maxvalue: the maximum value of the sequence. This + value is used when the CREATE SEQUENCE command is emitted to + the database as the value of the "MAXVALUE" clause. If ``None``, + the clause is omitted, which on most platforms indicates a + maxvalue of 2^63-1 and -1 for ascending and descending sequences, + respectively. + + :param nominvalue: no minimum value of the sequence. This + value is used when the CREATE SEQUENCE command is emitted to + the database as the value of the "NO MINVALUE" clause. If ``None``, + the clause is omitted, which on most platforms indicates a + minvalue of 1 and -2^63-1 for ascending and descending sequences, + respectively. + + :param nomaxvalue: no maximum value of the sequence. This + value is used when the CREATE SEQUENCE command is emitted to + the database as the value of the "NO MAXVALUE" clause. If ``None``, + the clause is omitted, which on most platforms indicates a + maxvalue of 2^63-1 and -1 for ascending and descending sequences, + respectively. + + :param cycle: allows the sequence to wrap around when the maxvalue + or minvalue has been reached by an ascending or descending sequence + respectively. This value is used when the CREATE SEQUENCE command + is emitted to the database as the "CYCLE" clause. If the limit is + reached, the next number generated will be the minvalue or maxvalue, + respectively. If cycle=False (the default) any calls to nextval + after the sequence has reached its maximum value will return an + error. + + :param schema: optional schema name for the sequence, if located + in a schema other than the default. The rules for selecting the + schema name when a :class:`_schema.MetaData` + is also present are the same + as that of :paramref:`_schema.Table.schema`. + + :param cache: optional integer value; number of future values in the + sequence which are calculated in advance. Renders the CACHE keyword + understood by Oracle and PostgreSQL. + + :param order: optional boolean value; if ``True``, renders the + ORDER keyword, understood by Oracle, indicating the sequence is + definitively ordered. May be necessary to provide deterministic + ordering using Oracle RAC. + + :param data_type: The type to be returned by the sequence, for + dialects that allow us to choose between INTEGER, BIGINT, etc. + (e.g., mssql). + + .. versionadded:: 1.4.0 + + :param optional: boolean value, when ``True``, indicates that this + :class:`.Sequence` object only needs to be explicitly generated + on backends that don't provide another way to generate primary + key identifiers. Currently, it essentially means, "don't create + this sequence on the PostgreSQL backend, where the SERIAL keyword + creates a sequence for us automatically". + :param quote: boolean value, when ``True`` or ``False``, explicitly + forces quoting of the :paramref:`_schema.Sequence.name` on or off. + When left at its default of ``None``, normal quoting rules based + on casing and reserved words take place. + :param quote_schema: Set the quoting preferences for the ``schema`` + name. + + :param metadata: optional :class:`_schema.MetaData` object which this + :class:`.Sequence` will be associated with. A :class:`.Sequence` + that is associated with a :class:`_schema.MetaData` + gains the following + capabilities: + + * The :class:`.Sequence` will inherit the + :paramref:`_schema.MetaData.schema` + parameter specified to the target :class:`_schema.MetaData`, which + affects the production of CREATE / DROP DDL, if any. + + * The :meth:`.Sequence.create` and :meth:`.Sequence.drop` methods + automatically use the engine bound to the :class:`_schema.MetaData` + object, if any. + + * The :meth:`_schema.MetaData.create_all` and + :meth:`_schema.MetaData.drop_all` + methods will emit CREATE / DROP for this :class:`.Sequence`, + even if the :class:`.Sequence` is not associated with any + :class:`_schema.Table` / :class:`_schema.Column` + that's a member of this + :class:`_schema.MetaData`. + + The above behaviors can only occur if the :class:`.Sequence` is + explicitly associated with the :class:`_schema.MetaData` + via this parameter. + + .. seealso:: + + :ref:`sequence_metadata` - full discussion of the + :paramref:`.Sequence.metadata` parameter. + + :param for_update: Indicates this :class:`.Sequence`, when associated + with a :class:`_schema.Column`, + should be invoked for UPDATE statements + on that column's table, rather than for INSERT statements, when + no value is otherwise present for that column in the statement. + + """ + DefaultGenerator.__init__(self, for_update=for_update) + IdentityOptions.__init__( + self, + start=start, + increment=increment, + minvalue=minvalue, + maxvalue=maxvalue, + nominvalue=nominvalue, + nomaxvalue=nomaxvalue, + cycle=cycle, + cache=cache, + order=order, + ) + self.column = None + self.name = quoted_name(name, quote) + self.optional = optional + if schema is BLANK_SCHEMA: + self.schema = schema = None + elif metadata is not None and schema is None and metadata.schema: + self.schema = schema = metadata.schema + else: + self.schema = quoted_name.construct(schema, quote_schema) + self.metadata = metadata + self._key = _get_table_key(name, schema) + if metadata: + self._set_metadata(metadata) + if data_type is not None: + self.data_type = to_instance(data_type) + else: + self.data_type = None + + @util.preload_module("sqlalchemy.sql.functions") + def next_value(self) -> Function[int]: + """Return a :class:`.next_value` function element + which will render the appropriate increment function + for this :class:`.Sequence` within any SQL expression. + + """ + return util.preloaded.sql_functions.func.next_value(self) + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + column = parent + assert isinstance(column, Column) + super()._set_parent(column) + column._on_table_attach(self._set_table) + + def _copy(self) -> Sequence: + return Sequence( + name=self.name, + start=self.start, + increment=self.increment, + minvalue=self.minvalue, + maxvalue=self.maxvalue, + nominvalue=self.nominvalue, + nomaxvalue=self.nomaxvalue, + cycle=self.cycle, + schema=self.schema, + cache=self.cache, + order=self.order, + data_type=self.data_type, + optional=self.optional, + metadata=self.metadata, + for_update=self.for_update, + ) + + def _set_table(self, column: Column[Any], table: Table) -> None: + self._set_metadata(table.metadata) + + def _set_metadata(self, metadata: MetaData) -> None: + self.metadata = metadata + self.metadata._sequences[self._key] = self + + def create(self, bind: _CreateDropBind, checkfirst: bool = True) -> None: + """Creates this sequence in the database.""" + + bind._run_ddl_visitor(ddl.SchemaGenerator, self, checkfirst=checkfirst) + + def drop(self, bind: _CreateDropBind, checkfirst: bool = True) -> None: + """Drops this sequence from the database.""" + + bind._run_ddl_visitor(ddl.SchemaDropper, self, checkfirst=checkfirst) + + def _not_a_column_expr(self) -> NoReturn: + raise exc.InvalidRequestError( + f"This {self.__class__.__name__} cannot be used directly " + "as a column expression. Use func.next_value(sequence) " + "to produce a 'next value' function that's usable " + "as a column element." + ) + + +@inspection._self_inspects +class FetchedValue(SchemaEventTarget): + """A marker for a transparent database-side default. + + Use :class:`.FetchedValue` when the database is configured + to provide some automatic default for a column. + + E.g.:: + + Column('foo', Integer, FetchedValue()) + + Would indicate that some trigger or default generator + will create a new value for the ``foo`` column during an + INSERT. + + .. seealso:: + + :ref:`triggered_columns` + + """ + + is_server_default = True + reflected = False + has_argument = False + is_clause_element = False + is_identity = False + + column: Optional[Column[Any]] + + def __init__(self, for_update: bool = False) -> None: + self.for_update = for_update + + def _as_for_update(self, for_update: bool) -> FetchedValue: + if for_update == self.for_update: + return self + else: + return self._clone(for_update) + + def _copy(self) -> FetchedValue: + return FetchedValue(self.for_update) + + def _clone(self, for_update: bool) -> Self: + n = self.__class__.__new__(self.__class__) + n.__dict__.update(self.__dict__) + n.__dict__.pop("column", None) + n.for_update = for_update + return n + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + column = parent + assert isinstance(column, Column) + self.column = column + if self.for_update: + self.column.server_onupdate = self + else: + self.column.server_default = self + + def __repr__(self) -> str: + return util.generic_repr(self) + + +class DefaultClause(FetchedValue): + """A DDL-specified DEFAULT column value. + + :class:`.DefaultClause` is a :class:`.FetchedValue` + that also generates a "DEFAULT" clause when + "CREATE TABLE" is emitted. + + :class:`.DefaultClause` is generated automatically + whenever the ``server_default``, ``server_onupdate`` arguments of + :class:`_schema.Column` are used. A :class:`.DefaultClause` + can be passed positionally as well. + + For example, the following:: + + Column('foo', Integer, server_default="50") + + Is equivalent to:: + + Column('foo', Integer, DefaultClause("50")) + + """ + + has_argument = True + + def __init__( + self, + arg: Union[str, ClauseElement, TextClause], + for_update: bool = False, + _reflected: bool = False, + ) -> None: + util.assert_arg_type(arg, (str, ClauseElement, TextClause), "arg") + super().__init__(for_update) + self.arg = arg + self.reflected = _reflected + + def _copy(self) -> DefaultClause: + return DefaultClause( + arg=self.arg, for_update=self.for_update, _reflected=self.reflected + ) + + def __repr__(self) -> str: + return "DefaultClause(%r, for_update=%r)" % (self.arg, self.for_update) + + +class Constraint(DialectKWArgs, HasConditionalDDL, SchemaItem): + """A table-level SQL constraint. + + :class:`_schema.Constraint` serves as the base class for the series of + constraint objects that can be associated with :class:`_schema.Table` + objects, including :class:`_schema.PrimaryKeyConstraint`, + :class:`_schema.ForeignKeyConstraint` + :class:`_schema.UniqueConstraint`, and + :class:`_schema.CheckConstraint`. + + """ + + __visit_name__ = "constraint" + + _creation_order: int + _column_flag: bool + + def __init__( + self, + name: _ConstraintNameArgument = None, + deferrable: Optional[bool] = None, + initially: Optional[str] = None, + info: Optional[_InfoType] = None, + comment: Optional[str] = None, + _create_rule: Optional[Any] = None, + _type_bound: bool = False, + **dialect_kw: Any, + ) -> None: + r"""Create a SQL constraint. + + :param name: + Optional, the in-database name of this ``Constraint``. + + :param deferrable: + Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when + issuing DDL for this constraint. + + :param initially: + Optional string. If set, emit INITIALLY <value> when issuing DDL + for this constraint. + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + :param comment: Optional string that will render an SQL comment on + foreign key constraint creation. + + .. versionadded:: 2.0 + + :param \**dialect_kw: Additional keyword arguments are dialect + specific, and passed in the form ``<dialectname>_<argname>``. See + the documentation regarding an individual dialect at + :ref:`dialect_toplevel` for detail on documented arguments. + + :param _create_rule: + used internally by some datatypes that also create constraints. + + :param _type_bound: + used internally to indicate that this constraint is associated with + a specific datatype. + + """ + + self.name = name + self.deferrable = deferrable + self.initially = initially + if info: + self.info = info + self._create_rule = _create_rule + self._type_bound = _type_bound + util.set_creation_order(self) + self._validate_dialect_kwargs(dialect_kw) + self.comment = comment + + def _should_create_for_compiler( + self, compiler: DDLCompiler, **kw: Any + ) -> bool: + if self._create_rule is not None and not self._create_rule(compiler): + return False + elif self._ddl_if is not None: + return self._ddl_if._should_execute( + ddl.CreateConstraint(self), self, None, compiler=compiler, **kw + ) + else: + return True + + @property + def table(self) -> Table: + try: + if isinstance(self.parent, Table): + return self.parent + except AttributeError: + pass + raise exc.InvalidRequestError( + "This constraint is not bound to a table. Did you " + "mean to call table.append_constraint(constraint) ?" + ) + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + assert isinstance(parent, (Table, Column)) + self.parent = parent + parent.constraints.add(self) + + @util.deprecated( + "1.4", + "The :meth:`_schema.Constraint.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy(self, **kw: Any) -> Self: + return self._copy(**kw) + + def _copy(self, **kw: Any) -> Self: + raise NotImplementedError() + + +class ColumnCollectionMixin: + """A :class:`_expression.ColumnCollection` of :class:`_schema.Column` + objects. + + This collection represents the columns which are referred to by + this object. + + """ + + _columns: DedupeColumnCollection[Column[Any]] + + _allow_multiple_tables = False + + _pending_colargs: List[Optional[Union[str, Column[Any]]]] + + if TYPE_CHECKING: + + def _set_parent_with_dispatch( + self, parent: SchemaEventTarget, **kw: Any + ) -> None: ... + + def __init__( + self, + *columns: _DDLColumnArgument, + _autoattach: bool = True, + _column_flag: bool = False, + _gather_expressions: Optional[ + List[Union[str, ColumnElement[Any]]] + ] = None, + ) -> None: + self._column_flag = _column_flag + self._columns = DedupeColumnCollection() + + processed_expressions: Optional[ + List[Union[ColumnElement[Any], str]] + ] = _gather_expressions + + if processed_expressions is not None: + self._pending_colargs = [] + for ( + expr, + _, + _, + add_element, + ) in coercions.expect_col_expression_collection( + roles.DDLConstraintColumnRole, columns + ): + self._pending_colargs.append(add_element) + processed_expressions.append(expr) + else: + self._pending_colargs = [ + coercions.expect(roles.DDLConstraintColumnRole, column) + for column in columns + ] + + if _autoattach and self._pending_colargs: + self._check_attach() + + def _check_attach(self, evt: bool = False) -> None: + col_objs = [c for c in self._pending_colargs if isinstance(c, Column)] + + cols_w_table = [c for c in col_objs if isinstance(c.table, Table)] + + cols_wo_table = set(col_objs).difference(cols_w_table) + if cols_wo_table: + # feature #3341 - place event listeners for Column objects + # such that when all those cols are attached, we autoattach. + assert not evt, "Should not reach here on event call" + + # issue #3411 - don't do the per-column auto-attach if some of the + # columns are specified as strings. + has_string_cols = { + c for c in self._pending_colargs if c is not None + }.difference(col_objs) + if not has_string_cols: + + def _col_attached(column: Column[Any], table: Table) -> None: + # this isinstance() corresponds with the + # isinstance() above; only want to count Table-bound + # columns + if isinstance(table, Table): + cols_wo_table.discard(column) + if not cols_wo_table: + self._check_attach(evt=True) + + self._cols_wo_table = cols_wo_table + for col in cols_wo_table: + col._on_table_attach(_col_attached) + return + + columns = cols_w_table + + tables = {c.table for c in columns} + if len(tables) == 1: + self._set_parent_with_dispatch(tables.pop()) + elif len(tables) > 1 and not self._allow_multiple_tables: + table = columns[0].table + others = [c for c in columns[1:] if c.table is not table] + if others: + # black could not format this inline + other_str = ", ".join("'%s'" % c for c in others) + raise exc.ArgumentError( + f"Column(s) {other_str} " + f"are not part of table '{table.description}'." + ) + + @util.ro_memoized_property + def columns(self) -> ReadOnlyColumnCollection[str, Column[Any]]: + return self._columns.as_readonly() + + @util.ro_memoized_property + def c(self) -> ReadOnlyColumnCollection[str, Column[Any]]: + return self._columns.as_readonly() + + def _col_expressions( + self, parent: Union[Table, Column[Any]] + ) -> List[Optional[Column[Any]]]: + if isinstance(parent, Column): + result: List[Optional[Column[Any]]] = [ + c for c in self._pending_colargs if isinstance(c, Column) + ] + assert len(result) == len(self._pending_colargs) + return result + else: + try: + return [ + parent.c[col] if isinstance(col, str) else col + for col in self._pending_colargs + ] + except KeyError as ke: + raise exc.ConstraintColumnNotFoundError( + f"Can't create {self.__class__.__name__} " + f"on table '{parent.description}': no column " + f"named '{ke.args[0]}' is present." + ) from ke + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + assert isinstance(parent, (Table, Column)) + + for col in self._col_expressions(parent): + if col is not None: + self._columns.add(col) + + +class ColumnCollectionConstraint(ColumnCollectionMixin, Constraint): + """A constraint that proxies a ColumnCollection.""" + + def __init__( + self, + *columns: _DDLColumnArgument, + name: _ConstraintNameArgument = None, + deferrable: Optional[bool] = None, + initially: Optional[str] = None, + info: Optional[_InfoType] = None, + _autoattach: bool = True, + _column_flag: bool = False, + _gather_expressions: Optional[List[_DDLColumnArgument]] = None, + **dialect_kw: Any, + ) -> None: + r""" + :param \*columns: + A sequence of column names or Column objects. + + :param name: + Optional, the in-database name of this constraint. + + :param deferrable: + Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when + issuing DDL for this constraint. + + :param initially: + Optional string. If set, emit INITIALLY <value> when issuing DDL + for this constraint. + + :param \**dialect_kw: other keyword arguments including + dialect-specific arguments are propagated to the :class:`.Constraint` + superclass. + + """ + Constraint.__init__( + self, + name=name, + deferrable=deferrable, + initially=initially, + info=info, + **dialect_kw, + ) + ColumnCollectionMixin.__init__( + self, *columns, _autoattach=_autoattach, _column_flag=_column_flag + ) + + columns: ReadOnlyColumnCollection[str, Column[Any]] + """A :class:`_expression.ColumnCollection` representing the set of columns + for this constraint. + + """ + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + assert isinstance(parent, (Column, Table)) + Constraint._set_parent(self, parent) + ColumnCollectionMixin._set_parent(self, parent) + + def __contains__(self, x: Any) -> bool: + return x in self._columns + + @util.deprecated( + "1.4", + "The :meth:`_schema.ColumnCollectionConstraint.copy` method " + "is deprecated and will be removed in a future release.", + ) + def copy( + self, + *, + target_table: Optional[Table] = None, + **kw: Any, + ) -> ColumnCollectionConstraint: + return self._copy(target_table=target_table, **kw) + + def _copy( + self, + *, + target_table: Optional[Table] = None, + **kw: Any, + ) -> ColumnCollectionConstraint: + # ticket #5276 + constraint_kwargs = {} + for dialect_name in self.dialect_options: + dialect_options = self.dialect_options[dialect_name]._non_defaults + for ( + dialect_option_key, + dialect_option_value, + ) in dialect_options.items(): + constraint_kwargs[dialect_name + "_" + dialect_option_key] = ( + dialect_option_value + ) + + assert isinstance(self.parent, Table) + c = self.__class__( + name=self.name, + deferrable=self.deferrable, + initially=self.initially, + *[ + _copy_expression(expr, self.parent, target_table) + for expr in self._columns + ], + comment=self.comment, + **constraint_kwargs, + ) + return self._schema_item_copy(c) + + def contains_column(self, col: Column[Any]) -> bool: + """Return True if this constraint contains the given column. + + Note that this object also contains an attribute ``.columns`` + which is a :class:`_expression.ColumnCollection` of + :class:`_schema.Column` objects. + + """ + + return self._columns.contains_column(col) + + def __iter__(self) -> Iterator[Column[Any]]: + return iter(self._columns) + + def __len__(self) -> int: + return len(self._columns) + + +class CheckConstraint(ColumnCollectionConstraint): + """A table- or column-level CHECK constraint. + + Can be included in the definition of a Table or Column. + """ + + _allow_multiple_tables = True + + __visit_name__ = "table_or_column_check_constraint" + + @_document_text_coercion( + "sqltext", + ":class:`.CheckConstraint`", + ":paramref:`.CheckConstraint.sqltext`", + ) + def __init__( + self, + sqltext: _TextCoercedExpressionArgument[Any], + name: _ConstraintNameArgument = None, + deferrable: Optional[bool] = None, + initially: Optional[str] = None, + table: Optional[Table] = None, + info: Optional[_InfoType] = None, + _create_rule: Optional[Any] = None, + _autoattach: bool = True, + _type_bound: bool = False, + **dialect_kw: Any, + ) -> None: + r"""Construct a CHECK constraint. + + :param sqltext: + A string containing the constraint definition, which will be used + verbatim, or a SQL expression construct. If given as a string, + the object is converted to a :func:`_expression.text` object. + If the textual + string includes a colon character, escape this using a backslash:: + + CheckConstraint(r"foo ~ E'a(?\:b|c)d") + + :param name: + Optional, the in-database name of the constraint. + + :param deferrable: + Optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when + issuing DDL for this constraint. + + :param initially: + Optional string. If set, emit INITIALLY <value> when issuing DDL + for this constraint. + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + """ + + self.sqltext = coercions.expect(roles.DDLExpressionRole, sqltext) + columns: List[Column[Any]] = [] + visitors.traverse(self.sqltext, {}, {"column": columns.append}) + + super().__init__( + name=name, + deferrable=deferrable, + initially=initially, + _create_rule=_create_rule, + info=info, + _type_bound=_type_bound, + _autoattach=_autoattach, + *columns, + **dialect_kw, + ) + if table is not None: + self._set_parent_with_dispatch(table) + + @property + def is_column_level(self) -> bool: + return not isinstance(self.parent, Table) + + @util.deprecated( + "1.4", + "The :meth:`_schema.CheckConstraint.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy( + self, *, target_table: Optional[Table] = None, **kw: Any + ) -> CheckConstraint: + return self._copy(target_table=target_table, **kw) + + def _copy( + self, *, target_table: Optional[Table] = None, **kw: Any + ) -> CheckConstraint: + if target_table is not None: + # note that target_table is None for the copy process of + # a column-bound CheckConstraint, so this path is not reached + # in that case. + sqltext = _copy_expression(self.sqltext, self.table, target_table) + else: + sqltext = self.sqltext + c = CheckConstraint( + sqltext, + name=self.name, + initially=self.initially, + deferrable=self.deferrable, + _create_rule=self._create_rule, + table=target_table, + comment=self.comment, + _autoattach=False, + _type_bound=self._type_bound, + ) + return self._schema_item_copy(c) + + +class ForeignKeyConstraint(ColumnCollectionConstraint): + """A table-level FOREIGN KEY constraint. + + Defines a single column or composite FOREIGN KEY ... REFERENCES + constraint. For a no-frills, single column foreign key, adding a + :class:`_schema.ForeignKey` to the definition of a :class:`_schema.Column` + is a + shorthand equivalent for an unnamed, single column + :class:`_schema.ForeignKeyConstraint`. + + Examples of foreign key configuration are in :ref:`metadata_foreignkeys`. + + """ + + __visit_name__ = "foreign_key_constraint" + + def __init__( + self, + columns: _typing_Sequence[_DDLColumnArgument], + refcolumns: _typing_Sequence[_DDLColumnArgument], + name: _ConstraintNameArgument = None, + onupdate: Optional[str] = None, + ondelete: Optional[str] = None, + deferrable: Optional[bool] = None, + initially: Optional[str] = None, + use_alter: bool = False, + link_to_name: bool = False, + match: Optional[str] = None, + table: Optional[Table] = None, + info: Optional[_InfoType] = None, + comment: Optional[str] = None, + **dialect_kw: Any, + ) -> None: + r"""Construct a composite-capable FOREIGN KEY. + + :param columns: A sequence of local column names. The named columns + must be defined and present in the parent Table. The names should + match the ``key`` given to each column (defaults to the name) unless + ``link_to_name`` is True. + + :param refcolumns: A sequence of foreign column names or Column + objects. The columns must all be located within the same Table. + + :param name: Optional, the in-database name of the key. + + :param onupdate: Optional string. If set, emit ON UPDATE <value> when + issuing DDL for this constraint. Typical values include CASCADE, + DELETE and RESTRICT. + + :param ondelete: Optional string. If set, emit ON DELETE <value> when + issuing DDL for this constraint. Typical values include CASCADE, + DELETE and RESTRICT. + + :param deferrable: Optional bool. If set, emit DEFERRABLE or NOT + DEFERRABLE when issuing DDL for this constraint. + + :param initially: Optional string. If set, emit INITIALLY <value> when + issuing DDL for this constraint. + + :param link_to_name: if True, the string name given in ``column`` is + the rendered name of the referenced column, not its locally assigned + ``key``. + + :param use_alter: If True, do not emit the DDL for this constraint as + part of the CREATE TABLE definition. Instead, generate it via an + ALTER TABLE statement issued after the full collection of tables + have been created, and drop it via an ALTER TABLE statement before + the full collection of tables are dropped. + + The use of :paramref:`_schema.ForeignKeyConstraint.use_alter` is + particularly geared towards the case where two or more tables + are established within a mutually-dependent foreign key constraint + relationship; however, the :meth:`_schema.MetaData.create_all` and + :meth:`_schema.MetaData.drop_all` + methods will perform this resolution + automatically, so the flag is normally not needed. + + .. seealso:: + + :ref:`use_alter` + + :param match: Optional string. If set, emit MATCH <value> when issuing + DDL for this constraint. Typical values include SIMPLE, PARTIAL + and FULL. + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + :param comment: Optional string that will render an SQL comment on + foreign key constraint creation. + + .. versionadded:: 2.0 + + :param \**dialect_kw: Additional keyword arguments are dialect + specific, and passed in the form ``<dialectname>_<argname>``. See + the documentation regarding an individual dialect at + :ref:`dialect_toplevel` for detail on documented arguments. + + """ + + Constraint.__init__( + self, + name=name, + deferrable=deferrable, + initially=initially, + info=info, + comment=comment, + **dialect_kw, + ) + self.onupdate = onupdate + self.ondelete = ondelete + self.link_to_name = link_to_name + self.use_alter = use_alter + self.match = match + + if len(set(columns)) != len(refcolumns): + if len(set(columns)) != len(columns): + # e.g. FOREIGN KEY (a, a) REFERENCES r (b, c) + raise exc.ArgumentError( + "ForeignKeyConstraint with duplicate source column " + "references are not supported." + ) + else: + # e.g. FOREIGN KEY (a) REFERENCES r (b, c) + # paraphrasing + # https://www.postgresql.org/docs/current/static/ddl-constraints.html + raise exc.ArgumentError( + "ForeignKeyConstraint number " + "of constrained columns must match the number of " + "referenced columns." + ) + + # standalone ForeignKeyConstraint - create + # associated ForeignKey objects which will be applied to hosted + # Column objects (in col.foreign_keys), either now or when attached + # to the Table for string-specified names + self.elements = [ + ForeignKey( + refcol, + _constraint=self, + name=self.name, + onupdate=self.onupdate, + ondelete=self.ondelete, + use_alter=self.use_alter, + link_to_name=self.link_to_name, + match=self.match, + deferrable=self.deferrable, + initially=self.initially, + **self.dialect_kwargs, + ) + for refcol in refcolumns + ] + + ColumnCollectionMixin.__init__(self, *columns) + if table is not None: + if hasattr(self, "parent"): + assert table is self.parent + self._set_parent_with_dispatch(table) + + def _append_element(self, column: Column[Any], fk: ForeignKey) -> None: + self._columns.add(column) + self.elements.append(fk) + + columns: ReadOnlyColumnCollection[str, Column[Any]] + """A :class:`_expression.ColumnCollection` representing the set of columns + for this constraint. + + """ + + elements: List[ForeignKey] + """A sequence of :class:`_schema.ForeignKey` objects. + + Each :class:`_schema.ForeignKey` + represents a single referring column/referred + column pair. + + This collection is intended to be read-only. + + """ + + @property + def _elements(self) -> util.OrderedDict[str, ForeignKey]: + # legacy - provide a dictionary view of (column_key, fk) + return util.OrderedDict(zip(self.column_keys, self.elements)) + + @property + def _referred_schema(self) -> Optional[str]: + for elem in self.elements: + return elem._referred_schema + else: + return None + + @property + def referred_table(self) -> Table: + """The :class:`_schema.Table` object to which this + :class:`_schema.ForeignKeyConstraint` references. + + This is a dynamically calculated attribute which may not be available + if the constraint and/or parent table is not yet associated with + a metadata collection that contains the referred table. + + """ + return self.elements[0].column.table + + def _validate_dest_table(self, table: Table) -> None: + table_keys = {elem._table_key() for elem in self.elements} + if None not in table_keys and len(table_keys) > 1: + elem0, elem1 = sorted(table_keys)[0:2] + raise exc.ArgumentError( + f"ForeignKeyConstraint on " + f"{table.fullname}({self._col_description}) refers to " + f"multiple remote tables: {elem0} and {elem1}" + ) + + @property + def column_keys(self) -> _typing_Sequence[str]: + """Return a list of string keys representing the local + columns in this :class:`_schema.ForeignKeyConstraint`. + + This list is either the original string arguments sent + to the constructor of the :class:`_schema.ForeignKeyConstraint`, + or if the constraint has been initialized with :class:`_schema.Column` + objects, is the string ``.key`` of each element. + + """ + if hasattr(self, "parent"): + return self._columns.keys() + else: + return [ + col.key if isinstance(col, ColumnElement) else str(col) + for col in self._pending_colargs + ] + + @property + def _col_description(self) -> str: + return ", ".join(self.column_keys) + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + table = parent + assert isinstance(table, Table) + Constraint._set_parent(self, table) + + ColumnCollectionConstraint._set_parent(self, table) + + for col, fk in zip(self._columns, self.elements): + if not hasattr(fk, "parent") or fk.parent is not col: + fk._set_parent_with_dispatch(col) + + self._validate_dest_table(table) + + @util.deprecated( + "1.4", + "The :meth:`_schema.ForeignKeyConstraint.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy( + self, + *, + schema: Optional[str] = None, + target_table: Optional[Table] = None, + **kw: Any, + ) -> ForeignKeyConstraint: + return self._copy(schema=schema, target_table=target_table, **kw) + + def _copy( + self, + *, + schema: Optional[str] = None, + target_table: Optional[Table] = None, + **kw: Any, + ) -> ForeignKeyConstraint: + fkc = ForeignKeyConstraint( + [x.parent.key for x in self.elements], + [ + x._get_colspec( + schema=schema, + table_name=( + target_table.name + if target_table is not None + and x._table_key() == x.parent.table.key + else None + ), + _is_copy=True, + ) + for x in self.elements + ], + name=self.name, + onupdate=self.onupdate, + ondelete=self.ondelete, + use_alter=self.use_alter, + deferrable=self.deferrable, + initially=self.initially, + link_to_name=self.link_to_name, + match=self.match, + comment=self.comment, + ) + for self_fk, other_fk in zip(self.elements, fkc.elements): + self_fk._schema_item_copy(other_fk) + return self._schema_item_copy(fkc) + + +class PrimaryKeyConstraint(ColumnCollectionConstraint): + """A table-level PRIMARY KEY constraint. + + The :class:`.PrimaryKeyConstraint` object is present automatically + on any :class:`_schema.Table` object; it is assigned a set of + :class:`_schema.Column` objects corresponding to those marked with + the :paramref:`_schema.Column.primary_key` flag:: + + >>> my_table = Table('mytable', metadata, + ... Column('id', Integer, primary_key=True), + ... Column('version_id', Integer, primary_key=True), + ... Column('data', String(50)) + ... ) + >>> my_table.primary_key + PrimaryKeyConstraint( + Column('id', Integer(), table=<mytable>, + primary_key=True, nullable=False), + Column('version_id', Integer(), table=<mytable>, + primary_key=True, nullable=False) + ) + + The primary key of a :class:`_schema.Table` can also be specified by using + a :class:`.PrimaryKeyConstraint` object explicitly; in this mode of usage, + the "name" of the constraint can also be specified, as well as other + options which may be recognized by dialects:: + + my_table = Table('mytable', metadata, + Column('id', Integer), + Column('version_id', Integer), + Column('data', String(50)), + PrimaryKeyConstraint('id', 'version_id', + name='mytable_pk') + ) + + The two styles of column-specification should generally not be mixed. + An warning is emitted if the columns present in the + :class:`.PrimaryKeyConstraint` + don't match the columns that were marked as ``primary_key=True``, if both + are present; in this case, the columns are taken strictly from the + :class:`.PrimaryKeyConstraint` declaration, and those columns otherwise + marked as ``primary_key=True`` are ignored. This behavior is intended to + be backwards compatible with previous behavior. + + For the use case where specific options are to be specified on the + :class:`.PrimaryKeyConstraint`, but the usual style of using + ``primary_key=True`` flags is still desirable, an empty + :class:`.PrimaryKeyConstraint` may be specified, which will take on the + primary key column collection from the :class:`_schema.Table` based on the + flags:: + + my_table = Table('mytable', metadata, + Column('id', Integer, primary_key=True), + Column('version_id', Integer, primary_key=True), + Column('data', String(50)), + PrimaryKeyConstraint(name='mytable_pk', + mssql_clustered=True) + ) + + """ + + __visit_name__ = "primary_key_constraint" + + def __init__( + self, + *columns: _DDLColumnArgument, + name: Optional[str] = None, + deferrable: Optional[bool] = None, + initially: Optional[str] = None, + info: Optional[_InfoType] = None, + _implicit_generated: bool = False, + **dialect_kw: Any, + ) -> None: + self._implicit_generated = _implicit_generated + super().__init__( + *columns, + name=name, + deferrable=deferrable, + initially=initially, + info=info, + **dialect_kw, + ) + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + table = parent + assert isinstance(table, Table) + super()._set_parent(table) + + if table.primary_key is not self: + table.constraints.discard(table.primary_key) + table.primary_key = self # type: ignore + table.constraints.add(self) + + table_pks = [c for c in table.c if c.primary_key] + if ( + self._columns + and table_pks + and set(table_pks) != set(self._columns) + ): + # black could not format these inline + table_pk_str = ", ".join("'%s'" % c.name for c in table_pks) + col_str = ", ".join("'%s'" % c.name for c in self._columns) + + util.warn( + f"Table '{table.name}' specifies columns " + f"{table_pk_str} as " + f"primary_key=True, " + f"not matching locally specified columns {col_str}; " + f"setting the " + f"current primary key columns to " + f"{col_str}. " + f"This warning " + f"may become an exception in a future release" + ) + table_pks[:] = [] + + for c in self._columns: + c.primary_key = True + if c._user_defined_nullable is NULL_UNSPECIFIED: + c.nullable = False + if table_pks: + self._columns.extend(table_pks) + + def _reload(self, columns: Iterable[Column[Any]]) -> None: + """repopulate this :class:`.PrimaryKeyConstraint` given + a set of columns. + + Existing columns in the table that are marked as primary_key=True + are maintained. + + Also fires a new event. + + This is basically like putting a whole new + :class:`.PrimaryKeyConstraint` object on the parent + :class:`_schema.Table` object without actually replacing the object. + + The ordering of the given list of columns is also maintained; these + columns will be appended to the list of columns after any which + are already present. + + """ + # set the primary key flag on new columns. + # note any existing PK cols on the table also have their + # flag still set. + for col in columns: + col.primary_key = True + + self._columns.extend(columns) + + PrimaryKeyConstraint._autoincrement_column._reset(self) # type: ignore + self._set_parent_with_dispatch(self.table) + + def _replace(self, col: Column[Any]) -> None: + PrimaryKeyConstraint._autoincrement_column._reset(self) # type: ignore + self._columns.replace(col) + + self.dispatch._sa_event_column_added_to_pk_constraint(self, col) + + @property + def columns_autoinc_first(self) -> List[Column[Any]]: + autoinc = self._autoincrement_column + + if autoinc is not None: + return [autoinc] + [c for c in self._columns if c is not autoinc] + else: + return list(self._columns) + + @util.ro_memoized_property + def _autoincrement_column(self) -> Optional[Column[int]]: + def _validate_autoinc(col: Column[Any], autoinc_true: bool) -> bool: + if col.type._type_affinity is None or not issubclass( + col.type._type_affinity, + ( + type_api.INTEGERTYPE._type_affinity, + type_api.NUMERICTYPE._type_affinity, + ), + ): + if autoinc_true: + raise exc.ArgumentError( + f"Column type {col.type} on column '{col}' is not " + f"compatible with autoincrement=True" + ) + else: + return False + elif ( + not isinstance(col.default, (type(None), Sequence)) + and not autoinc_true + ): + return False + elif ( + col.server_default is not None + and not isinstance(col.server_default, Identity) + and not autoinc_true + ): + return False + elif col.foreign_keys and col.autoincrement not in ( + True, + "ignore_fk", + ): + return False + return True + + if len(self._columns) == 1: + col = list(self._columns)[0] + + if col.autoincrement is True: + _validate_autoinc(col, True) + return col + elif col.autoincrement in ( + "auto", + "ignore_fk", + ) and _validate_autoinc(col, False): + return col + else: + return None + + else: + autoinc = None + for col in self._columns: + if col.autoincrement is True: + _validate_autoinc(col, True) + if autoinc is not None: + raise exc.ArgumentError( + f"Only one Column may be marked " + f"autoincrement=True, found both " + f"{col.name} and {autoinc.name}." + ) + else: + autoinc = col + + return autoinc + + +class UniqueConstraint(ColumnCollectionConstraint): + """A table-level UNIQUE constraint. + + Defines a single column or composite UNIQUE constraint. For a no-frills, + single column constraint, adding ``unique=True`` to the ``Column`` + definition is a shorthand equivalent for an unnamed, single column + UniqueConstraint. + """ + + __visit_name__ = "unique_constraint" + + +class Index( + DialectKWArgs, ColumnCollectionMixin, HasConditionalDDL, SchemaItem +): + """A table-level INDEX. + + Defines a composite (one or more column) INDEX. + + E.g.:: + + sometable = Table("sometable", metadata, + Column("name", String(50)), + Column("address", String(100)) + ) + + Index("some_index", sometable.c.name) + + For a no-frills, single column index, adding + :class:`_schema.Column` also supports ``index=True``:: + + sometable = Table("sometable", metadata, + Column("name", String(50), index=True) + ) + + For a composite index, multiple columns can be specified:: + + Index("some_index", sometable.c.name, sometable.c.address) + + Functional indexes are supported as well, typically by using the + :data:`.func` construct in conjunction with table-bound + :class:`_schema.Column` objects:: + + Index("some_index", func.lower(sometable.c.name)) + + An :class:`.Index` can also be manually associated with a + :class:`_schema.Table`, + either through inline declaration or using + :meth:`_schema.Table.append_constraint`. When this approach is used, + the names + of the indexed columns can be specified as strings:: + + Table("sometable", metadata, + Column("name", String(50)), + Column("address", String(100)), + Index("some_index", "name", "address") + ) + + To support functional or expression-based indexes in this form, the + :func:`_expression.text` construct may be used:: + + from sqlalchemy import text + + Table("sometable", metadata, + Column("name", String(50)), + Column("address", String(100)), + Index("some_index", text("lower(name)")) + ) + + .. seealso:: + + :ref:`schema_indexes` - General information on :class:`.Index`. + + :ref:`postgresql_indexes` - PostgreSQL-specific options available for + the :class:`.Index` construct. + + :ref:`mysql_indexes` - MySQL-specific options available for the + :class:`.Index` construct. + + :ref:`mssql_indexes` - MSSQL-specific options available for the + :class:`.Index` construct. + + """ + + __visit_name__ = "index" + + table: Optional[Table] + expressions: _typing_Sequence[Union[str, ColumnElement[Any]]] + _table_bound_expressions: _typing_Sequence[ColumnElement[Any]] + + def __init__( + self, + name: Optional[str], + *expressions: _DDLColumnArgument, + unique: bool = False, + quote: Optional[bool] = None, + info: Optional[_InfoType] = None, + _table: Optional[Table] = None, + _column_flag: bool = False, + **dialect_kw: Any, + ) -> None: + r"""Construct an index object. + + :param name: + The name of the index + + :param \*expressions: + Column expressions to include in the index. The expressions + are normally instances of :class:`_schema.Column`, but may also + be arbitrary SQL expressions which ultimately refer to a + :class:`_schema.Column`. + + :param unique=False: + Keyword only argument; if True, create a unique index. + + :param quote=None: + Keyword only argument; whether to apply quoting to the name of + the index. Works in the same manner as that of + :paramref:`_schema.Column.quote`. + + :param info=None: Optional data dictionary which will be populated + into the :attr:`.SchemaItem.info` attribute of this object. + + :param \**dialect_kw: Additional keyword arguments not mentioned above + are dialect specific, and passed in the form + ``<dialectname>_<argname>``. See the documentation regarding an + individual dialect at :ref:`dialect_toplevel` for detail on + documented arguments. + + """ + self.table = table = None + + self.name = quoted_name.construct(name, quote) + self.unique = unique + if info is not None: + self.info = info + + # TODO: consider "table" argument being public, but for + # the purpose of the fix here, it starts as private. + if _table is not None: + table = _table + + self._validate_dialect_kwargs(dialect_kw) + + self.expressions = [] + # will call _set_parent() if table-bound column + # objects are present + ColumnCollectionMixin.__init__( + self, + *expressions, + _column_flag=_column_flag, + _gather_expressions=self.expressions, + ) + if table is not None: + self._set_parent(table) + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + table = parent + assert isinstance(table, Table) + ColumnCollectionMixin._set_parent(self, table) + + if self.table is not None and table is not self.table: + raise exc.ArgumentError( + f"Index '{self.name}' is against table " + f"'{self.table.description}', and " + f"cannot be associated with table '{table.description}'." + ) + self.table = table + table.indexes.add(self) + + expressions = self.expressions + col_expressions = self._col_expressions(table) + assert len(expressions) == len(col_expressions) + + exprs = [] + for expr, colexpr in zip(expressions, col_expressions): + if isinstance(expr, ClauseElement): + exprs.append(expr) + elif colexpr is not None: + exprs.append(colexpr) + else: + assert False + self.expressions = self._table_bound_expressions = exprs + + def create(self, bind: _CreateDropBind, checkfirst: bool = False) -> None: + """Issue a ``CREATE`` statement for this + :class:`.Index`, using the given + :class:`.Connection` or :class:`.Engine`` for connectivity. + + .. seealso:: + + :meth:`_schema.MetaData.create_all`. + + """ + bind._run_ddl_visitor(ddl.SchemaGenerator, self, checkfirst=checkfirst) + + def drop(self, bind: _CreateDropBind, checkfirst: bool = False) -> None: + """Issue a ``DROP`` statement for this + :class:`.Index`, using the given + :class:`.Connection` or :class:`.Engine` for connectivity. + + .. seealso:: + + :meth:`_schema.MetaData.drop_all`. + + """ + bind._run_ddl_visitor(ddl.SchemaDropper, self, checkfirst=checkfirst) + + def __repr__(self) -> str: + exprs: _typing_Sequence[Any] # noqa: F842 + + return "Index(%s)" % ( + ", ".join( + [repr(self.name)] + + [repr(e) for e in self.expressions] + + (self.unique and ["unique=True"] or []) + ) + ) + + +_NamingSchemaCallable = Callable[[Constraint, Table], str] +_NamingSchemaDirective = Union[str, _NamingSchemaCallable] + + +class _NamingSchemaTD(TypedDict, total=False): + fk: _NamingSchemaDirective + pk: _NamingSchemaDirective + ix: _NamingSchemaDirective + ck: _NamingSchemaDirective + uq: _NamingSchemaDirective + + +_NamingSchemaParameter = Union[ + # it seems like the TypedDict here is useful for pylance typeahead, + # and not much else + _NamingSchemaTD, + # there is no form that allows Union[Type[Any], str] to work in all + # cases, including breaking out Mapping[] entries for each combination + # even, therefore keys must be `Any` (see #10264) + Mapping[Any, _NamingSchemaDirective], +] + + +DEFAULT_NAMING_CONVENTION: _NamingSchemaParameter = util.immutabledict( + {"ix": "ix_%(column_0_label)s"} +) + + +class MetaData(HasSchemaAttr): + """A collection of :class:`_schema.Table` + objects and their associated schema + constructs. + + Holds a collection of :class:`_schema.Table` objects as well as + an optional binding to an :class:`_engine.Engine` or + :class:`_engine.Connection`. If bound, the :class:`_schema.Table` objects + in the collection and their columns may participate in implicit SQL + execution. + + The :class:`_schema.Table` objects themselves are stored in the + :attr:`_schema.MetaData.tables` dictionary. + + :class:`_schema.MetaData` is a thread-safe object for read operations. + Construction of new tables within a single :class:`_schema.MetaData` + object, + either explicitly or via reflection, may not be completely thread-safe. + + .. seealso:: + + :ref:`metadata_describing` - Introduction to database metadata + + """ + + __visit_name__ = "metadata" + + def __init__( + self, + schema: Optional[str] = None, + quote_schema: Optional[bool] = None, + naming_convention: Optional[_NamingSchemaParameter] = None, + info: Optional[_InfoType] = None, + ) -> None: + """Create a new MetaData object. + + :param schema: + The default schema to use for the :class:`_schema.Table`, + :class:`.Sequence`, and potentially other objects associated with + this :class:`_schema.MetaData`. Defaults to ``None``. + + .. seealso:: + + :ref:`schema_metadata_schema_name` - details on how the + :paramref:`_schema.MetaData.schema` parameter is used. + + :paramref:`_schema.Table.schema` + + :paramref:`.Sequence.schema` + + :param quote_schema: + Sets the ``quote_schema`` flag for those :class:`_schema.Table`, + :class:`.Sequence`, and other objects which make usage of the + local ``schema`` name. + + :param info: Optional data dictionary which will be populated into the + :attr:`.SchemaItem.info` attribute of this object. + + :param naming_convention: a dictionary referring to values which + will establish default naming conventions for :class:`.Constraint` + and :class:`.Index` objects, for those objects which are not given + a name explicitly. + + The keys of this dictionary may be: + + * a constraint or Index class, e.g. the :class:`.UniqueConstraint`, + :class:`_schema.ForeignKeyConstraint` class, the :class:`.Index` + class + + * a string mnemonic for one of the known constraint classes; + ``"fk"``, ``"pk"``, ``"ix"``, ``"ck"``, ``"uq"`` for foreign key, + primary key, index, check, and unique constraint, respectively. + + * the string name of a user-defined "token" that can be used + to define new naming tokens. + + The values associated with each "constraint class" or "constraint + mnemonic" key are string naming templates, such as + ``"uq_%(table_name)s_%(column_0_name)s"``, + which describe how the name should be composed. The values + associated with user-defined "token" keys should be callables of the + form ``fn(constraint, table)``, which accepts the constraint/index + object and :class:`_schema.Table` as arguments, returning a string + result. + + The built-in names are as follows, some of which may only be + available for certain types of constraint: + + * ``%(table_name)s`` - the name of the :class:`_schema.Table` + object + associated with the constraint. + + * ``%(referred_table_name)s`` - the name of the + :class:`_schema.Table` + object associated with the referencing target of a + :class:`_schema.ForeignKeyConstraint`. + + * ``%(column_0_name)s`` - the name of the :class:`_schema.Column` + at + index position "0" within the constraint. + + * ``%(column_0N_name)s`` - the name of all :class:`_schema.Column` + objects in order within the constraint, joined without a + separator. + + * ``%(column_0_N_name)s`` - the name of all + :class:`_schema.Column` + objects in order within the constraint, joined with an + underscore as a separator. + + * ``%(column_0_label)s``, ``%(column_0N_label)s``, + ``%(column_0_N_label)s`` - the label of either the zeroth + :class:`_schema.Column` or all :class:`.Columns`, separated with + or without an underscore + + * ``%(column_0_key)s``, ``%(column_0N_key)s``, + ``%(column_0_N_key)s`` - the key of either the zeroth + :class:`_schema.Column` or all :class:`.Columns`, separated with + or without an underscore + + * ``%(referred_column_0_name)s``, ``%(referred_column_0N_name)s`` + ``%(referred_column_0_N_name)s``, ``%(referred_column_0_key)s``, + ``%(referred_column_0N_key)s``, ... column tokens which + render the names/keys/labels of columns that are referenced + by a :class:`_schema.ForeignKeyConstraint`. + + * ``%(constraint_name)s`` - a special key that refers to the + existing name given to the constraint. When this key is + present, the :class:`.Constraint` object's existing name will be + replaced with one that is composed from template string that + uses this token. When this token is present, it is required that + the :class:`.Constraint` is given an explicit name ahead of time. + + * user-defined: any additional token may be implemented by passing + it along with a ``fn(constraint, table)`` callable to the + naming_convention dictionary. + + .. versionadded:: 1.3.0 - added new ``%(column_0N_name)s``, + ``%(column_0_N_name)s``, and related tokens that produce + concatenations of names, keys, or labels for all columns referred + to by a given constraint. + + .. seealso:: + + :ref:`constraint_naming_conventions` - for detailed usage + examples. + + """ + if schema is not None and not isinstance(schema, str): + raise exc.ArgumentError( + "expected schema argument to be a string, " + f"got {type(schema)}." + ) + self.tables = util.FacadeDict() + self.schema = quoted_name.construct(schema, quote_schema) + self.naming_convention = ( + naming_convention + if naming_convention + else DEFAULT_NAMING_CONVENTION + ) + if info: + self.info = info + self._schemas: Set[str] = set() + self._sequences: Dict[str, Sequence] = {} + self._fk_memos: Dict[Tuple[str, Optional[str]], List[ForeignKey]] = ( + collections.defaultdict(list) + ) + + tables: util.FacadeDict[str, Table] + """A dictionary of :class:`_schema.Table` + objects keyed to their name or "table key". + + The exact key is that determined by the :attr:`_schema.Table.key` + attribute; + for a table with no :attr:`_schema.Table.schema` attribute, + this is the same + as :attr:`_schema.Table.name`. For a table with a schema, + it is typically of the + form ``schemaname.tablename``. + + .. seealso:: + + :attr:`_schema.MetaData.sorted_tables` + + """ + + def __repr__(self) -> str: + return "MetaData()" + + def __contains__(self, table_or_key: Union[str, Table]) -> bool: + if not isinstance(table_or_key, str): + table_or_key = table_or_key.key + return table_or_key in self.tables + + def _add_table( + self, name: str, schema: Optional[str], table: Table + ) -> None: + key = _get_table_key(name, schema) + self.tables._insert_item(key, table) + if schema: + self._schemas.add(schema) + + def _remove_table(self, name: str, schema: Optional[str]) -> None: + key = _get_table_key(name, schema) + removed = dict.pop(self.tables, key, None) + if removed is not None: + for fk in removed.foreign_keys: + fk._remove_from_metadata(self) + if self._schemas: + self._schemas = { + t.schema for t in self.tables.values() if t.schema is not None + } + + def __getstate__(self) -> Dict[str, Any]: + return { + "tables": self.tables, + "schema": self.schema, + "schemas": self._schemas, + "sequences": self._sequences, + "fk_memos": self._fk_memos, + "naming_convention": self.naming_convention, + } + + def __setstate__(self, state: Dict[str, Any]) -> None: + self.tables = state["tables"] + self.schema = state["schema"] + self.naming_convention = state["naming_convention"] + self._sequences = state["sequences"] + self._schemas = state["schemas"] + self._fk_memos = state["fk_memos"] + + def clear(self) -> None: + """Clear all Table objects from this MetaData.""" + + dict.clear(self.tables) # type: ignore + self._schemas.clear() + self._fk_memos.clear() + + def remove(self, table: Table) -> None: + """Remove the given Table object from this MetaData.""" + + self._remove_table(table.name, table.schema) + + @property + def sorted_tables(self) -> List[Table]: + """Returns a list of :class:`_schema.Table` objects sorted in order of + foreign key dependency. + + The sorting will place :class:`_schema.Table` + objects that have dependencies + first, before the dependencies themselves, representing the + order in which they can be created. To get the order in which + the tables would be dropped, use the ``reversed()`` Python built-in. + + .. warning:: + + The :attr:`.MetaData.sorted_tables` attribute cannot by itself + accommodate automatic resolution of dependency cycles between + tables, which are usually caused by mutually dependent foreign key + constraints. When these cycles are detected, the foreign keys + of these tables are omitted from consideration in the sort. + A warning is emitted when this condition occurs, which will be an + exception raise in a future release. Tables which are not part + of the cycle will still be returned in dependency order. + + To resolve these cycles, the + :paramref:`_schema.ForeignKeyConstraint.use_alter` parameter may be + applied to those constraints which create a cycle. Alternatively, + the :func:`_schema.sort_tables_and_constraints` function will + automatically return foreign key constraints in a separate + collection when cycles are detected so that they may be applied + to a schema separately. + + .. versionchanged:: 1.3.17 - a warning is emitted when + :attr:`.MetaData.sorted_tables` cannot perform a proper sort + due to cyclical dependencies. This will be an exception in a + future release. Additionally, the sort will continue to return + other tables not involved in the cycle in dependency order which + was not the case previously. + + .. seealso:: + + :func:`_schema.sort_tables` + + :func:`_schema.sort_tables_and_constraints` + + :attr:`_schema.MetaData.tables` + + :meth:`_reflection.Inspector.get_table_names` + + :meth:`_reflection.Inspector.get_sorted_table_and_fkc_names` + + + """ + return ddl.sort_tables( + sorted(self.tables.values(), key=lambda t: t.key) # type: ignore + ) + + @util.preload_module("sqlalchemy.engine.reflection") + def reflect( + self, + bind: Union[Engine, Connection], + schema: Optional[str] = None, + views: bool = False, + only: Union[ + _typing_Sequence[str], Callable[[str, MetaData], bool], None + ] = None, + extend_existing: bool = False, + autoload_replace: bool = True, + resolve_fks: bool = True, + **dialect_kwargs: Any, + ) -> None: + r"""Load all available table definitions from the database. + + Automatically creates ``Table`` entries in this ``MetaData`` for any + table available in the database but not yet present in the + ``MetaData``. May be called multiple times to pick up tables recently + added to the database, however no special action is taken if a table + in this ``MetaData`` no longer exists in the database. + + :param bind: + A :class:`.Connection` or :class:`.Engine` used to access the + database. + + :param schema: + Optional, query and reflect tables from an alternate schema. + If None, the schema associated with this :class:`_schema.MetaData` + is used, if any. + + :param views: + If True, also reflect views (materialized and plain). + + :param only: + Optional. Load only a sub-set of available named tables. May be + specified as a sequence of names or a callable. + + If a sequence of names is provided, only those tables will be + reflected. An error is raised if a table is requested but not + available. Named tables already present in this ``MetaData`` are + ignored. + + If a callable is provided, it will be used as a boolean predicate to + filter the list of potential table names. The callable is called + with a table name and this ``MetaData`` instance as positional + arguments and should return a true value for any table to reflect. + + :param extend_existing: Passed along to each :class:`_schema.Table` as + :paramref:`_schema.Table.extend_existing`. + + :param autoload_replace: Passed along to each :class:`_schema.Table` + as + :paramref:`_schema.Table.autoload_replace`. + + :param resolve_fks: if True, reflect :class:`_schema.Table` + objects linked + to :class:`_schema.ForeignKey` objects located in each + :class:`_schema.Table`. + For :meth:`_schema.MetaData.reflect`, + this has the effect of reflecting + related tables that might otherwise not be in the list of tables + being reflected, for example if the referenced table is in a + different schema or is omitted via the + :paramref:`.MetaData.reflect.only` parameter. When False, + :class:`_schema.ForeignKey` objects are not followed to the + :class:`_schema.Table` + in which they link, however if the related table is also part of the + list of tables that would be reflected in any case, the + :class:`_schema.ForeignKey` object will still resolve to its related + :class:`_schema.Table` after the :meth:`_schema.MetaData.reflect` + operation is + complete. Defaults to True. + + .. versionadded:: 1.3.0 + + .. seealso:: + + :paramref:`_schema.Table.resolve_fks` + + :param \**dialect_kwargs: Additional keyword arguments not mentioned + above are dialect specific, and passed in the form + ``<dialectname>_<argname>``. See the documentation regarding an + individual dialect at :ref:`dialect_toplevel` for detail on + documented arguments. + + .. seealso:: + + :ref:`metadata_reflection_toplevel` + + :meth:`_events.DDLEvents.column_reflect` - Event used to customize + the reflected columns. Usually used to generalize the types using + :meth:`_types.TypeEngine.as_generic` + + :ref:`metadata_reflection_dbagnostic_types` - describes how to + reflect tables using general types. + + """ + + with inspection.inspect(bind)._inspection_context() as insp: + reflect_opts: Any = { + "autoload_with": insp, + "extend_existing": extend_existing, + "autoload_replace": autoload_replace, + "resolve_fks": resolve_fks, + "_extend_on": set(), + } + + reflect_opts.update(dialect_kwargs) + + if schema is None: + schema = self.schema + + if schema is not None: + reflect_opts["schema"] = schema + + kind = util.preloaded.engine_reflection.ObjectKind.TABLE + available: util.OrderedSet[str] = util.OrderedSet( + insp.get_table_names(schema) + ) + if views: + kind = util.preloaded.engine_reflection.ObjectKind.ANY + available.update(insp.get_view_names(schema)) + try: + available.update(insp.get_materialized_view_names(schema)) + except NotImplementedError: + pass + + if schema is not None: + available_w_schema: util.OrderedSet[str] = util.OrderedSet( + [f"{schema}.{name}" for name in available] + ) + else: + available_w_schema = available + + current = set(self.tables) + + if only is None: + load = [ + name + for name, schname in zip(available, available_w_schema) + if extend_existing or schname not in current + ] + elif callable(only): + load = [ + name + for name, schname in zip(available, available_w_schema) + if (extend_existing or schname not in current) + and only(name, self) + ] + else: + missing = [name for name in only if name not in available] + if missing: + s = schema and (" schema '%s'" % schema) or "" + missing_str = ", ".join(missing) + raise exc.InvalidRequestError( + f"Could not reflect: requested table(s) not available " + f"in {bind.engine!r}{s}: ({missing_str})" + ) + load = [ + name + for name in only + if extend_existing or name not in current + ] + # pass the available tables so the inspector can + # choose to ignore the filter_names + _reflect_info = insp._get_reflection_info( + schema=schema, + filter_names=load, + available=available, + kind=kind, + scope=util.preloaded.engine_reflection.ObjectScope.ANY, + **dialect_kwargs, + ) + reflect_opts["_reflect_info"] = _reflect_info + + for name in load: + try: + Table(name, self, **reflect_opts) + except exc.UnreflectableTableError as uerr: + util.warn(f"Skipping table {name}: {uerr}") + + def create_all( + self, + bind: _CreateDropBind, + tables: Optional[_typing_Sequence[Table]] = None, + checkfirst: bool = True, + ) -> None: + """Create all tables stored in this metadata. + + Conditional by default, will not attempt to recreate tables already + present in the target database. + + :param bind: + A :class:`.Connection` or :class:`.Engine` used to access the + database. + + :param tables: + Optional list of ``Table`` objects, which is a subset of the total + tables in the ``MetaData`` (others are ignored). + + :param checkfirst: + Defaults to True, don't issue CREATEs for tables already present + in the target database. + + """ + bind._run_ddl_visitor( + ddl.SchemaGenerator, self, checkfirst=checkfirst, tables=tables + ) + + def drop_all( + self, + bind: _CreateDropBind, + tables: Optional[_typing_Sequence[Table]] = None, + checkfirst: bool = True, + ) -> None: + """Drop all tables stored in this metadata. + + Conditional by default, will not attempt to drop tables not present in + the target database. + + :param bind: + A :class:`.Connection` or :class:`.Engine` used to access the + database. + + :param tables: + Optional list of ``Table`` objects, which is a subset of the + total tables in the ``MetaData`` (others are ignored). + + :param checkfirst: + Defaults to True, only issue DROPs for tables confirmed to be + present in the target database. + + """ + bind._run_ddl_visitor( + ddl.SchemaDropper, self, checkfirst=checkfirst, tables=tables + ) + + +class Computed(FetchedValue, SchemaItem): + """Defines a generated column, i.e. "GENERATED ALWAYS AS" syntax. + + The :class:`.Computed` construct is an inline construct added to the + argument list of a :class:`_schema.Column` object:: + + from sqlalchemy import Computed + + Table('square', metadata_obj, + Column('side', Float, nullable=False), + Column('area', Float, Computed('side * side')) + ) + + See the linked documentation below for complete details. + + .. versionadded:: 1.3.11 + + .. seealso:: + + :ref:`computed_ddl` + + """ + + __visit_name__ = "computed_column" + + column: Optional[Column[Any]] + + @_document_text_coercion( + "sqltext", ":class:`.Computed`", ":paramref:`.Computed.sqltext`" + ) + def __init__( + self, sqltext: _DDLColumnArgument, persisted: Optional[bool] = None + ) -> None: + """Construct a GENERATED ALWAYS AS DDL construct to accompany a + :class:`_schema.Column`. + + :param sqltext: + A string containing the column generation expression, which will be + used verbatim, or a SQL expression construct, such as a + :func:`_expression.text` + object. If given as a string, the object is converted to a + :func:`_expression.text` object. + + :param persisted: + Optional, controls how this column should be persisted by the + database. Possible values are: + + * ``None``, the default, it will use the default persistence + defined by the database. + * ``True``, will render ``GENERATED ALWAYS AS ... STORED``, or the + equivalent for the target database if supported. + * ``False``, will render ``GENERATED ALWAYS AS ... VIRTUAL``, or + the equivalent for the target database if supported. + + Specifying ``True`` or ``False`` may raise an error when the DDL + is emitted to the target database if the database does not support + that persistence option. Leaving this parameter at its default + of ``None`` is guaranteed to succeed for all databases that support + ``GENERATED ALWAYS AS``. + + """ + self.sqltext = coercions.expect(roles.DDLExpressionRole, sqltext) + self.persisted = persisted + self.column = None + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + assert isinstance(parent, Column) + + if not isinstance( + parent.server_default, (type(None), Computed) + ) or not isinstance(parent.server_onupdate, (type(None), Computed)): + raise exc.ArgumentError( + "A generated column cannot specify a server_default or a " + "server_onupdate argument" + ) + self.column = parent + parent.computed = self + self.column.server_onupdate = self + self.column.server_default = self + + def _as_for_update(self, for_update: bool) -> FetchedValue: + return self + + @util.deprecated( + "1.4", + "The :meth:`_schema.Computed.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy( + self, *, target_table: Optional[Table] = None, **kw: Any + ) -> Computed: + return self._copy(target_table=target_table, **kw) + + def _copy( + self, *, target_table: Optional[Table] = None, **kw: Any + ) -> Computed: + sqltext = _copy_expression( + self.sqltext, + self.column.table if self.column is not None else None, + target_table, + ) + g = Computed(sqltext, persisted=self.persisted) + + return self._schema_item_copy(g) + + +class Identity(IdentityOptions, FetchedValue, SchemaItem): + """Defines an identity column, i.e. "GENERATED { ALWAYS | BY DEFAULT } + AS IDENTITY" syntax. + + The :class:`.Identity` construct is an inline construct added to the + argument list of a :class:`_schema.Column` object:: + + from sqlalchemy import Identity + + Table('foo', metadata_obj, + Column('id', Integer, Identity()) + Column('description', Text), + ) + + See the linked documentation below for complete details. + + .. versionadded:: 1.4 + + .. seealso:: + + :ref:`identity_ddl` + + """ + + __visit_name__ = "identity_column" + + is_identity = True + + def __init__( + self, + always: bool = False, + on_null: Optional[bool] = None, + start: Optional[int] = None, + increment: Optional[int] = None, + minvalue: Optional[int] = None, + maxvalue: Optional[int] = None, + nominvalue: Optional[bool] = None, + nomaxvalue: Optional[bool] = None, + cycle: Optional[bool] = None, + cache: Optional[int] = None, + order: Optional[bool] = None, + ) -> None: + """Construct a GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY DDL + construct to accompany a :class:`_schema.Column`. + + See the :class:`.Sequence` documentation for a complete description + of most parameters. + + .. note:: + MSSQL supports this construct as the preferred alternative to + generate an IDENTITY on a column, but it uses non standard + syntax that only support :paramref:`_schema.Identity.start` + and :paramref:`_schema.Identity.increment`. + All other parameters are ignored. + + :param always: + A boolean, that indicates the type of identity column. + If ``False`` is specified, the default, then the user-specified + value takes precedence. + If ``True`` is specified, a user-specified value is not accepted ( + on some backends, like PostgreSQL, OVERRIDING SYSTEM VALUE, or + similar, may be specified in an INSERT to override the sequence + value). + Some backends also have a default value for this parameter, + ``None`` can be used to omit rendering this part in the DDL. It + will be treated as ``False`` if a backend does not have a default + value. + + :param on_null: + Set to ``True`` to specify ON NULL in conjunction with a + ``always=False`` identity column. This option is only supported on + some backends, like Oracle. + + :param start: the starting index of the sequence. + :param increment: the increment value of the sequence. + :param minvalue: the minimum value of the sequence. + :param maxvalue: the maximum value of the sequence. + :param nominvalue: no minimum value of the sequence. + :param nomaxvalue: no maximum value of the sequence. + :param cycle: allows the sequence to wrap around when the maxvalue + or minvalue has been reached. + :param cache: optional integer value; number of future values in the + sequence which are calculated in advance. + :param order: optional boolean value; if true, renders the + ORDER keyword. + + """ + IdentityOptions.__init__( + self, + start=start, + increment=increment, + minvalue=minvalue, + maxvalue=maxvalue, + nominvalue=nominvalue, + nomaxvalue=nomaxvalue, + cycle=cycle, + cache=cache, + order=order, + ) + self.always = always + self.on_null = on_null + self.column = None + + def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None: + assert isinstance(parent, Column) + if not isinstance( + parent.server_default, (type(None), Identity) + ) or not isinstance(parent.server_onupdate, type(None)): + raise exc.ArgumentError( + "A column with an Identity object cannot specify a " + "server_default or a server_onupdate argument" + ) + if parent.autoincrement is False: + raise exc.ArgumentError( + "A column with an Identity object cannot specify " + "autoincrement=False" + ) + self.column = parent + + parent.identity = self + if parent._user_defined_nullable is NULL_UNSPECIFIED: + parent.nullable = False + + parent.server_default = self + + def _as_for_update(self, for_update: bool) -> FetchedValue: + return self + + @util.deprecated( + "1.4", + "The :meth:`_schema.Identity.copy` method is deprecated " + "and will be removed in a future release.", + ) + def copy(self, **kw: Any) -> Identity: + return self._copy(**kw) + + def _copy(self, **kw: Any) -> Identity: + i = Identity( + always=self.always, + on_null=self.on_null, + start=self.start, + increment=self.increment, + minvalue=self.minvalue, + maxvalue=self.maxvalue, + nominvalue=self.nominvalue, + nomaxvalue=self.nomaxvalue, + cycle=self.cycle, + cache=self.cache, + order=self.order, + ) + + return self._schema_item_copy(i) |