# ext/asyncio/engine.py # Copyright (C) 2020-2024 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php from __future__ import annotations import asyncio import contextlib from typing import Any from typing import AsyncIterator from typing import Callable from typing import Dict from typing import Generator from typing import NoReturn from typing import Optional from typing import overload from typing import Tuple from typing import Type from typing import TYPE_CHECKING from typing import TypeVar from typing import Union from . import exc as async_exc from .base import asyncstartablecontext from .base import GeneratorStartableContext from .base import ProxyComparable from .base import StartableContext from .result import _ensure_sync_result from .result import AsyncResult from .result import AsyncScalarResult from ... import exc from ... import inspection from ... import util from ...engine import Connection from ...engine import create_engine as _create_engine from ...engine import create_pool_from_url as _create_pool_from_url from ...engine import Engine from ...engine.base import NestedTransaction from ...engine.base import Transaction from ...exc import ArgumentError from ...util.concurrency import greenlet_spawn from ...util.typing import Concatenate from ...util.typing import ParamSpec if TYPE_CHECKING: from ...engine.cursor import CursorResult from ...engine.interfaces import _CoreAnyExecuteParams from ...engine.interfaces import _CoreSingleExecuteParams from ...engine.interfaces import _DBAPIAnyExecuteParams from ...engine.interfaces import _ExecuteOptions from ...engine.interfaces import CompiledCacheType from ...engine.interfaces import CoreExecuteOptionsParameter from ...engine.interfaces import Dialect from ...engine.interfaces import IsolationLevel from ...engine.interfaces import SchemaTranslateMapType from ...engine.result import ScalarResult from ...engine.url import URL from ...pool import Pool from ...pool import PoolProxiedConnection from ...sql._typing import _InfoType from ...sql.base import Executable from ...sql.selectable import TypedReturnsRows _P = ParamSpec("_P") _T = TypeVar("_T", bound=Any) def create_async_engine(url: Union[str, URL], **kw: Any) -> AsyncEngine: """Create a new async engine instance. Arguments passed to :func:`_asyncio.create_async_engine` are mostly identical to those passed to the :func:`_sa.create_engine` function. The specified dialect must be an asyncio-compatible dialect such as :ref:`dialect-postgresql-asyncpg`. .. versionadded:: 1.4 :param async_creator: an async callable which returns a driver-level asyncio connection. If given, the function should take no arguments, and return a new asyncio connection from the underlying asyncio database driver; the connection will be wrapped in the appropriate structures to be used with the :class:`.AsyncEngine`. Note that the parameters specified in the URL are not applied here, and the creator function should use its own connection parameters. This parameter is the asyncio equivalent of the :paramref:`_sa.create_engine.creator` parameter of the :func:`_sa.create_engine` function. .. versionadded:: 2.0.16 """ if kw.get("server_side_cursors", False): raise async_exc.AsyncMethodRequired( "Can't set server_side_cursors for async engine globally; " "use the connection.stream() method for an async " "streaming result set" ) kw["_is_async"] = True async_creator = kw.pop("async_creator", None) if async_creator: if kw.get("creator", None): raise ArgumentError( "Can only specify one of 'async_creator' or 'creator', " "not both." ) def creator() -> Any: # note that to send adapted arguments like # prepared_statement_cache_size, user would use # "creator" and emulate this form here return sync_engine.dialect.dbapi.connect( # type: ignore async_creator_fn=async_creator ) kw["creator"] = creator sync_engine = _create_engine(url, **kw) return AsyncEngine(sync_engine) def async_engine_from_config( configuration: Dict[str, Any], prefix: str = "sqlalchemy.", **kwargs: Any ) -> AsyncEngine: """Create a new AsyncEngine instance using a configuration dictionary. This function is analogous to the :func:`_sa.engine_from_config` function in SQLAlchemy Core, except that the requested dialect must be an asyncio-compatible dialect such as :ref:`dialect-postgresql-asyncpg`. The argument signature of the function is identical to that of :func:`_sa.engine_from_config`. .. versionadded:: 1.4.29 """ options = { key[len(prefix) :]: value for key, value in configuration.items() if key.startswith(prefix) } options["_coerce_config"] = True options.update(kwargs) url = options.pop("url") return create_async_engine(url, **options) def create_async_pool_from_url(url: Union[str, URL], **kwargs: Any) -> Pool: """Create a new async engine instance. Arguments passed to :func:`_asyncio.create_async_pool_from_url` are mostly identical to those passed to the :func:`_sa.create_pool_from_url` function. The specified dialect must be an asyncio-compatible dialect such as :ref:`dialect-postgresql-asyncpg`. .. versionadded:: 2.0.10 """ kwargs["_is_async"] = True return _create_pool_from_url(url, **kwargs) class AsyncConnectable: __slots__ = "_slots_dispatch", "__weakref__" @classmethod def _no_async_engine_events(cls) -> NoReturn: raise NotImplementedError( "asynchronous events are not implemented at this time. Apply " "synchronous listeners to the AsyncEngine.sync_engine or " "AsyncConnection.sync_connection attributes." ) @util.create_proxy_methods( Connection, ":class:`_engine.Connection`", ":class:`_asyncio.AsyncConnection`", classmethods=[], methods=[], attributes=[ "closed", "invalidated", "dialect", "default_isolation_level", ], ) class AsyncConnection( ProxyComparable[Connection], StartableContext["AsyncConnection"], AsyncConnectable, ): """An asyncio proxy for a :class:`_engine.Connection`. :class:`_asyncio.AsyncConnection` is acquired using the :meth:`_asyncio.AsyncEngine.connect` method of :class:`_asyncio.AsyncEngine`:: from sqlalchemy.ext.asyncio import create_async_engine engine = create_async_engine("postgresql+asyncpg://user:pass@host/dbname") async with engine.connect() as conn: result = await conn.execute(select(table)) .. versionadded:: 1.4 """ # noqa # AsyncConnection is a thin proxy; no state should be added here # that is not retrievable from the "sync" engine / connection, e.g. # current transaction, info, etc. It should be possible to # create a new AsyncConnection that matches this one given only the # "sync" elements. __slots__ = ( "engine", "sync_engine", "sync_connection", ) def __init__( self, async_engine: AsyncEngine, sync_connection: Optional[Connection] = None, ): self.engine = async_engine self.sync_engine = async_engine.sync_engine self.sync_connection = self._assign_proxied(sync_connection) sync_connection: Optional[Connection] """Reference to the sync-style :class:`_engine.Connection` this :class:`_asyncio.AsyncConnection` proxies requests towards. This instance can be used as an event target. .. seealso:: :ref:`asyncio_events` """ sync_engine: Engine """Reference to the sync-style :class:`_engine.Engine` this :class:`_asyncio.AsyncConnection` is associated with via its underlying :class:`_engine.Connection`. This instance can be used as an event target. .. seealso:: :ref:`asyncio_events` """ @classmethod def _regenerate_proxy_for_target( cls, target: Connection ) -> AsyncConnection: return AsyncConnection( AsyncEngine._retrieve_proxy_for_target(target.engine), target ) async def start( self, is_ctxmanager: bool = False # noqa: U100 ) -> AsyncConnection: """Start this :class:`_asyncio.AsyncConnection` object's context outside of using a Python ``with:`` block. """ if self.sync_connection: raise exc.InvalidRequestError("connection is already started") self.sync_connection = self._assign_proxied( await greenlet_spawn(self.sync_engine.connect) ) return self @property def connection(self) -> NoReturn: """Not implemented for async; call :meth:`_asyncio.AsyncConnection.get_raw_connection`. """ raise exc.InvalidRequestError( "AsyncConnection.connection accessor is not implemented as the " "attribute may need to reconnect on an invalidated connection. " "Use the get_raw_connection() method." ) async def get_raw_connection(self) -> PoolProxiedConnection: """Return the pooled DBAPI-level connection in use by this :class:`_asyncio.AsyncConnection`. This is a SQLAlchemy connection-pool proxied connection which then has the attribute :attr:`_pool._ConnectionFairy.driver_connection` that refers to the actual driver connection. Its :attr:`_pool._ConnectionFairy.dbapi_connection` refers instead to an :class:`_engine.AdaptedConnection` instance that adapts the driver connection to the DBAPI protocol. """ return await greenlet_spawn(getattr, self._proxied, "connection") @util.ro_non_memoized_property def info(self) -> _InfoType: """Return the :attr:`_engine.Connection.info` dictionary of the underlying :class:`_engine.Connection`. This dictionary is freely writable for user-defined state to be associated with the database connection. This attribute is only available if the :class:`.AsyncConnection` is currently connected. If the :attr:`.AsyncConnection.closed` attribute is ``True``, then accessing this attribute will raise :class:`.ResourceClosedError`. .. versionadded:: 1.4.0b2 """ return self._proxied.info @util.ro_non_memoized_property def _proxied(self) -> Connection: if not self.sync_connection: self._raise_for_not_started() return self.sync_connection def begin(self) -> AsyncTransaction: """Begin a transaction prior to autobegin occurring.""" assert self._proxied return AsyncTransaction(self) def begin_nested(self) -> AsyncTransaction: """Begin a nested transaction and return a transaction handle.""" assert self._proxied return AsyncTransaction(self, nested=True) async def invalidate( self, exception: Optional[BaseException] = None ) -> None: """Invalidate the underlying DBAPI connection associated with this :class:`_engine.Connection`. See the method :meth:`_engine.Connection.invalidate` for full detail on this method. """ return await greenlet_spawn( self._proxied.invalidate, exception=exception ) async def get_isolation_level(self) -> IsolationLevel: return await greenlet_spawn(self._proxied.get_isolation_level) def in_transaction(self) -> bool: """Return True if a transaction is in progress.""" return self._proxied.in_transaction() def in_nested_transaction(self) -> bool: """Return True if a transaction is in progress. .. versionadded:: 1.4.0b2 """ return self._proxied.in_nested_transaction() def get_transaction(self) -> Optional[AsyncTransaction]: """Return an :class:`.AsyncTransaction` representing the current transaction, if any. This makes use of the underlying synchronous connection's :meth:`_engine.Connection.get_transaction` method to get the current :class:`_engine.Transaction`, which is then proxied in a new :class:`.AsyncTransaction` object. .. versionadded:: 1.4.0b2 """ trans = self._proxied.get_transaction() if trans is not None: return AsyncTransaction._retrieve_proxy_for_target(trans) else: return None def get_nested_transaction(self) -> Optional[AsyncTransaction]: """Return an :class:`.AsyncTransaction` representing the current nested (savepoint) transaction, if any. This makes use of the underlying synchronous connection's :meth:`_engine.Connection.get_nested_transaction` method to get the current :class:`_engine.Transaction`, which is then proxied in a new :class:`.AsyncTransaction` object. .. versionadded:: 1.4.0b2 """ trans = self._proxied.get_nested_transaction() if trans is not None: return AsyncTransaction._retrieve_proxy_for_target(trans) else: return None @overload async def execution_options( self, *, compiled_cache: Optional[CompiledCacheType] = ..., logging_token: str = ..., isolation_level: IsolationLevel = ..., no_parameters: bool = False, stream_results: bool = False, max_row_buffer: int = ..., yield_per: int = ..., insertmanyvalues_page_size: int = ..., schema_translate_map: Optional[SchemaTranslateMapType] = ..., preserve_rowcount: bool = False, **opt: Any, ) -> AsyncConnection: ... @overload async def execution_options(self, **opt: Any) -> AsyncConnection: ... async def execution_options(self, **opt: Any) -> AsyncConnection: r"""Set non-SQL options for the connection which take effect during execution. This returns this :class:`_asyncio.AsyncConnection` object with the new options added. See :meth:`_engine.Connection.execution_options` for full details on this method. """ conn = self._proxied c2 = await greenlet_spawn(conn.execution_options, **opt) assert c2 is conn return self async def commit(self) -> None: """Commit the transaction that is currently in progress. This method commits the current transaction if one has been started. If no transaction was started, the method has no effect, assuming the connection is in a non-invalidated state. A transaction is begun on a :class:`_engine.Connection` automatically whenever a statement is first executed, or when the :meth:`_engine.Connection.begin` method is called. """ await greenlet_spawn(self._proxied.commit) async def rollback(self) -> None: """Roll back the transaction that is currently in progress. This method rolls back the current transaction if one has been started. If no transaction was started, the method has no effect. If a transaction was started and the connection is in an invalidated state, the transaction is cleared using this method. A transaction is begun on a :class:`_engine.Connection` automatically whenever a statement is first executed, or when the :meth:`_engine.Connection.begin` method is called. """ await greenlet_spawn(self._proxied.rollback) async def close(self) -> None: """Close this :class:`_asyncio.AsyncConnection`. This has the effect of also rolling back the transaction if one is in place. """ await greenlet_spawn(self._proxied.close) async def aclose(self) -> None: """A synonym for :meth:`_asyncio.AsyncConnection.close`. The :meth:`_asyncio.AsyncConnection.aclose` name is specifically to support the Python standard library ``@contextlib.aclosing`` context manager function. .. versionadded:: 2.0.20 """ await self.close() async def exec_driver_sql( self, statement: str, parameters: Optional[_DBAPIAnyExecuteParams] = None, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[Any]: r"""Executes a driver-level SQL string and return buffered :class:`_engine.Result`. """ result = await greenlet_spawn( self._proxied.exec_driver_sql, statement, parameters, execution_options, _require_await=True, ) return await _ensure_sync_result(result, self.exec_driver_sql) @overload def stream( self, statement: TypedReturnsRows[_T], parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> GeneratorStartableContext[AsyncResult[_T]]: ... @overload def stream( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> GeneratorStartableContext[AsyncResult[Any]]: ... @asyncstartablecontext async def stream( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> AsyncIterator[AsyncResult[Any]]: """Execute a statement and return an awaitable yielding a :class:`_asyncio.AsyncResult` object. E.g.:: result = await conn.stream(stmt): async for row in result: print(f"{row}") The :meth:`.AsyncConnection.stream` method supports optional context manager use against the :class:`.AsyncResult` object, as in:: async with conn.stream(stmt) as result: async for row in result: print(f"{row}") In the above pattern, the :meth:`.AsyncResult.close` method is invoked unconditionally, even if the iterator is interrupted by an exception throw. Context manager use remains optional, however, and the function may be called in either an ``async with fn():`` or ``await fn()`` style. .. versionadded:: 2.0.0b3 added context manager support :return: an awaitable object that will yield an :class:`_asyncio.AsyncResult` object. .. seealso:: :meth:`.AsyncConnection.stream_scalars` """ if not self.dialect.supports_server_side_cursors: raise exc.InvalidRequestError( "Cant use `stream` or `stream_scalars` with the current " "dialect since it does not support server side cursors." ) result = await greenlet_spawn( self._proxied.execute, statement, parameters, execution_options=util.EMPTY_DICT.merge_with( execution_options, {"stream_results": True} ), _require_await=True, ) assert result.context._is_server_side ar = AsyncResult(result) try: yield ar except GeneratorExit: pass else: task = asyncio.create_task(ar.close()) await asyncio.shield(task) @overload async def execute( self, statement: TypedReturnsRows[_T], parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[_T]: ... @overload async def execute( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[Any]: ... async def execute( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[Any]: r"""Executes a SQL statement construct and return a buffered :class:`_engine.Result`. :param object: The statement to be executed. This is always an object that is in both the :class:`_expression.ClauseElement` and :class:`_expression.Executable` hierarchies, including: * :class:`_expression.Select` * :class:`_expression.Insert`, :class:`_expression.Update`, :class:`_expression.Delete` * :class:`_expression.TextClause` and :class:`_expression.TextualSelect` * :class:`_schema.DDL` and objects which inherit from :class:`_schema.ExecutableDDLElement` :param parameters: parameters which will be bound into the statement. This may be either a dictionary of parameter names to values, or a mutable sequence (e.g. a list) of dictionaries. When a list of dictionaries is passed, the underlying statement execution will make use of the DBAPI ``cursor.executemany()`` method. When a single dictionary is passed, the DBAPI ``cursor.execute()`` method will be used. :param execution_options: optional dictionary of execution options, which will be associated with the statement execution. This dictionary can provide a subset of the options that are accepted by :meth:`_engine.Connection.execution_options`. :return: a :class:`_engine.Result` object. """ result = await greenlet_spawn( self._proxied.execute, statement, parameters, execution_options=execution_options, _require_await=True, ) return await _ensure_sync_result(result, self.execute) @overload async def scalar( self, statement: TypedReturnsRows[Tuple[_T]], parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> Optional[_T]: ... @overload async def scalar( self, statement: Executable, parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> Any: ... async def scalar( self, statement: Executable, parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> Any: r"""Executes a SQL statement construct and returns a scalar object. This method is shorthand for invoking the :meth:`_engine.Result.scalar` method after invoking the :meth:`_engine.Connection.execute` method. Parameters are equivalent. :return: a scalar Python value representing the first column of the first row returned. """ result = await self.execute( statement, parameters, execution_options=execution_options ) return result.scalar() @overload async def scalars( self, statement: TypedReturnsRows[Tuple[_T]], parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> ScalarResult[_T]: ... @overload async def scalars( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> ScalarResult[Any]: ... async def scalars( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> ScalarResult[Any]: r"""Executes a SQL statement construct and returns a scalar objects. This method is shorthand for invoking the :meth:`_engine.Result.scalars` method after invoking the :meth:`_engine.Connection.execute` method. Parameters are equivalent. :return: a :class:`_engine.ScalarResult` object. .. versionadded:: 1.4.24 """ result = await self.execute( statement, parameters, execution_options=execution_options ) return result.scalars() @overload def stream_scalars( self, statement: TypedReturnsRows[Tuple[_T]], parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> GeneratorStartableContext[AsyncScalarResult[_T]]: ... @overload def stream_scalars( self, statement: Executable, parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> GeneratorStartableContext[AsyncScalarResult[Any]]: ... @asyncstartablecontext async def stream_scalars( self, statement: Executable, parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> AsyncIterator[AsyncScalarResult[Any]]: r"""Execute a statement and return an awaitable yielding a :class:`_asyncio.AsyncScalarResult` object. E.g.:: result = await conn.stream_scalars(stmt) async for scalar in result: print(f"{scalar}") This method is shorthand for invoking the :meth:`_engine.AsyncResult.scalars` method after invoking the :meth:`_engine.Connection.stream` method. Parameters are equivalent. The :meth:`.AsyncConnection.stream_scalars` method supports optional context manager use against the :class:`.AsyncScalarResult` object, as in:: async with conn.stream_scalars(stmt) as result: async for scalar in result: print(f"{scalar}") In the above pattern, the :meth:`.AsyncScalarResult.close` method is invoked unconditionally, even if the iterator is interrupted by an exception throw. Context manager use remains optional, however, and the function may be called in either an ``async with fn():`` or ``await fn()`` style. .. versionadded:: 2.0.0b3 added context manager support :return: an awaitable object that will yield an :class:`_asyncio.AsyncScalarResult` object. .. versionadded:: 1.4.24 .. seealso:: :meth:`.AsyncConnection.stream` """ async with self.stream( statement, parameters, execution_options=execution_options ) as result: yield result.scalars() async def run_sync( self, fn: Callable[Concatenate[Connection, _P], _T], *arg: _P.args, **kw: _P.kwargs, ) -> _T: """Invoke the given synchronous (i.e. not async) callable, passing a synchronous-style :class:`_engine.Connection` as the first argument. This method allows traditional synchronous SQLAlchemy functions to run within the context of an asyncio application. E.g.:: def do_something_with_core(conn: Connection, arg1: int, arg2: str) -> str: '''A synchronous function that does not require awaiting :param conn: a Core SQLAlchemy Connection, used synchronously :return: an optional return value is supported ''' conn.execute( some_table.insert().values(int_col=arg1, str_col=arg2) ) return "success" async def do_something_async(async_engine: AsyncEngine) -> None: '''an async function that uses awaiting''' async with async_engine.begin() as async_conn: # run do_something_with_core() with a sync-style # Connection, proxied into an awaitable return_code = await async_conn.run_sync(do_something_with_core, 5, "strval") print(return_code) This method maintains the asyncio event loop all the way through to the database connection by running the given callable in a specially instrumented greenlet. The most rudimentary use of :meth:`.AsyncConnection.run_sync` is to invoke methods such as :meth:`_schema.MetaData.create_all`, given an :class:`.AsyncConnection` that needs to be provided to :meth:`_schema.MetaData.create_all` as a :class:`_engine.Connection` object:: # run metadata.create_all(conn) with a sync-style Connection, # proxied into an awaitable with async_engine.begin() as conn: await conn.run_sync(metadata.create_all) .. note:: The provided callable is invoked inline within the asyncio event loop, and will block on traditional IO calls. IO within this callable should only call into SQLAlchemy's asyncio database APIs which will be properly adapted to the greenlet context. .. seealso:: :meth:`.AsyncSession.run_sync` :ref:`session_run_sync` """ # noqa: E501 return await greenlet_spawn( fn, self._proxied, *arg, _require_await=False, **kw ) def __await__(self) -> Generator[Any, None, AsyncConnection]: return self.start().__await__() async def __aexit__(self, type_: Any, value: Any, traceback: Any) -> None: task = asyncio.create_task(self.close()) await asyncio.shield(task) # START PROXY METHODS AsyncConnection # code within this block is **programmatically, # statically generated** by tools/generate_proxy_methods.py @property def closed(self) -> Any: r"""Return True if this connection is closed. .. container:: class_bases Proxied for the :class:`_engine.Connection` class on behalf of the :class:`_asyncio.AsyncConnection` class. """ # noqa: E501 return self._proxied.closed @property def invalidated(self) -> Any: r"""Return True if this connection was invalidated. .. container:: class_bases Proxied for the :class:`_engine.Connection` class on behalf of the :class:`_asyncio.AsyncConnection` class. This does not indicate whether or not the connection was invalidated at the pool level, however """ # noqa: E501 return self._proxied.invalidated @property def dialect(self) -> Dialect: r"""Proxy for the :attr:`_engine.Connection.dialect` attribute on behalf of the :class:`_asyncio.AsyncConnection` class. """ # noqa: E501 return self._proxied.dialect @dialect.setter def dialect(self, attr: Dialect) -> None: self._proxied.dialect = attr @property def default_isolation_level(self) -> Any: r"""The initial-connection time isolation level associated with the :class:`_engine.Dialect` in use. .. container:: class_bases Proxied for the :class:`_engine.Connection` class on behalf of the :class:`_asyncio.AsyncConnection` class. This value is independent of the :paramref:`.Connection.execution_options.isolation_level` and :paramref:`.Engine.execution_options.isolation_level` execution options, and is determined by the :class:`_engine.Dialect` when the first connection is created, by performing a SQL query against the database for the current isolation level before any additional commands have been emitted. Calling this accessor does not invoke any new SQL queries. .. seealso:: :meth:`_engine.Connection.get_isolation_level` - view current actual isolation level :paramref:`_sa.create_engine.isolation_level` - set per :class:`_engine.Engine` isolation level :paramref:`.Connection.execution_options.isolation_level` - set per :class:`_engine.Connection` isolation level """ # noqa: E501 return self._proxied.default_isolation_level # END PROXY METHODS AsyncConnection @util.create_proxy_methods( Engine, ":class:`_engine.Engine`", ":class:`_asyncio.AsyncEngine`", classmethods=[], methods=[ "clear_compiled_cache", "update_execution_options", "get_execution_options", ], attributes=["url", "pool", "dialect", "engine", "name", "driver", "echo"], ) class AsyncEngine(ProxyComparable[Engine], AsyncConnectable): """An asyncio proxy for a :class:`_engine.Engine`. :class:`_asyncio.AsyncEngine` is acquired using the :func:`_asyncio.create_async_engine` function:: from sqlalchemy.ext.asyncio import create_async_engine engine = create_async_engine("postgresql+asyncpg://user:pass@host/dbname") .. versionadded:: 1.4 """ # noqa # AsyncEngine is a thin proxy; no state should be added here # that is not retrievable from the "sync" engine / connection, e.g. # current transaction, info, etc. It should be possible to # create a new AsyncEngine that matches this one given only the # "sync" elements. __slots__ = "sync_engine" _connection_cls: Type[AsyncConnection] = AsyncConnection sync_engine: Engine """Reference to the sync-style :class:`_engine.Engine` this :class:`_asyncio.AsyncEngine` proxies requests towards. This instance can be used as an event target. .. seealso:: :ref:`asyncio_events` """ def __init__(self, sync_engine: Engine): if not sync_engine.dialect.is_async: raise exc.InvalidRequestError( "The asyncio extension requires an async driver to be used. " f"The loaded {sync_engine.dialect.driver!r} is not async." ) self.sync_engine = self._assign_proxied(sync_engine) @util.ro_non_memoized_property def _proxied(self) -> Engine: return self.sync_engine @classmethod def _regenerate_proxy_for_target(cls, target: Engine) -> AsyncEngine: return AsyncEngine(target) @contextlib.asynccontextmanager async def begin(self) -> AsyncIterator[AsyncConnection]: """Return a context manager which when entered will deliver an :class:`_asyncio.AsyncConnection` with an :class:`_asyncio.AsyncTransaction` established. E.g.:: async with async_engine.begin() as conn: await conn.execute( text("insert into table (x, y, z) values (1, 2, 3)") ) await conn.execute(text("my_special_procedure(5)")) """ conn = self.connect() async with conn: async with conn.begin(): yield conn def connect(self) -> AsyncConnection: """Return an :class:`_asyncio.AsyncConnection` object. The :class:`_asyncio.AsyncConnection` will procure a database connection from the underlying connection pool when it is entered as an async context manager:: async with async_engine.connect() as conn: result = await conn.execute(select(user_table)) The :class:`_asyncio.AsyncConnection` may also be started outside of a context manager by invoking its :meth:`_asyncio.AsyncConnection.start` method. """ return self._connection_cls(self) async def raw_connection(self) -> PoolProxiedConnection: """Return a "raw" DBAPI connection from the connection pool. .. seealso:: :ref:`dbapi_connections` """ return await greenlet_spawn(self.sync_engine.raw_connection) @overload def execution_options( self, *, compiled_cache: Optional[CompiledCacheType] = ..., logging_token: str = ..., isolation_level: IsolationLevel = ..., insertmanyvalues_page_size: int = ..., schema_translate_map: Optional[SchemaTranslateMapType] = ..., **opt: Any, ) -> AsyncEngine: ... @overload def execution_options(self, **opt: Any) -> AsyncEngine: ... def execution_options(self, **opt: Any) -> AsyncEngine: """Return a new :class:`_asyncio.AsyncEngine` that will provide :class:`_asyncio.AsyncConnection` objects with the given execution options. Proxied from :meth:`_engine.Engine.execution_options`. See that method for details. """ return AsyncEngine(self.sync_engine.execution_options(**opt)) async def dispose(self, close: bool = True) -> None: """Dispose of the connection pool used by this :class:`_asyncio.AsyncEngine`. :param close: if left at its default of ``True``, has the effect of fully closing all **currently checked in** database connections. Connections that are still checked out will **not** be closed, however they will no longer be associated with this :class:`_engine.Engine`, so when they are closed individually, eventually the :class:`_pool.Pool` which they are associated with will be garbage collected and they will be closed out fully, if not already closed on checkin. If set to ``False``, the previous connection pool is de-referenced, and otherwise not touched in any way. .. seealso:: :meth:`_engine.Engine.dispose` """ await greenlet_spawn(self.sync_engine.dispose, close=close) # START PROXY METHODS AsyncEngine # code within this block is **programmatically, # statically generated** by tools/generate_proxy_methods.py def clear_compiled_cache(self) -> None: r"""Clear the compiled cache associated with the dialect. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. This applies **only** to the built-in cache that is established via the :paramref:`_engine.create_engine.query_cache_size` parameter. It will not impact any dictionary caches that were passed via the :paramref:`.Connection.execution_options.compiled_cache` parameter. .. versionadded:: 1.4 """ # noqa: E501 return self._proxied.clear_compiled_cache() def update_execution_options(self, **opt: Any) -> None: r"""Update the default execution_options dictionary of this :class:`_engine.Engine`. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. The given keys/values in \**opt are added to the default execution options that will be used for all connections. The initial contents of this dictionary can be sent via the ``execution_options`` parameter to :func:`_sa.create_engine`. .. seealso:: :meth:`_engine.Connection.execution_options` :meth:`_engine.Engine.execution_options` """ # noqa: E501 return self._proxied.update_execution_options(**opt) def get_execution_options(self) -> _ExecuteOptions: r"""Get the non-SQL options which will take effect during execution. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. .. versionadded: 1.3 .. seealso:: :meth:`_engine.Engine.execution_options` """ # noqa: E501 return self._proxied.get_execution_options() @property def url(self) -> URL: r"""Proxy for the :attr:`_engine.Engine.url` attribute on behalf of the :class:`_asyncio.AsyncEngine` class. """ # noqa: E501 return self._proxied.url @url.setter def url(self, attr: URL) -> None: self._proxied.url = attr @property def pool(self) -> Pool: r"""Proxy for the :attr:`_engine.Engine.pool` attribute on behalf of the :class:`_asyncio.AsyncEngine` class. """ # noqa: E501 return self._proxied.pool @pool.setter def pool(self, attr: Pool) -> None: self._proxied.pool = attr @property def dialect(self) -> Dialect: r"""Proxy for the :attr:`_engine.Engine.dialect` attribute on behalf of the :class:`_asyncio.AsyncEngine` class. """ # noqa: E501 return self._proxied.dialect @dialect.setter def dialect(self, attr: Dialect) -> None: self._proxied.dialect = attr @property def engine(self) -> Any: r"""Returns this :class:`.Engine`. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. Used for legacy schemes that accept :class:`.Connection` / :class:`.Engine` objects within the same variable. """ # noqa: E501 return self._proxied.engine @property def name(self) -> Any: r"""String name of the :class:`~sqlalchemy.engine.interfaces.Dialect` in use by this :class:`Engine`. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. """ # noqa: E501 return self._proxied.name @property def driver(self) -> Any: r"""Driver name of the :class:`~sqlalchemy.engine.interfaces.Dialect` in use by this :class:`Engine`. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. """ # noqa: E501 return self._proxied.driver @property def echo(self) -> Any: r"""When ``True``, enable log output for this element. .. container:: class_bases Proxied for the :class:`_engine.Engine` class on behalf of the :class:`_asyncio.AsyncEngine` class. This has the effect of setting the Python logging level for the namespace of this element's class and object reference. A value of boolean ``True`` indicates that the loglevel ``logging.INFO`` will be set for the logger, whereas the string value ``debug`` will set the loglevel to ``logging.DEBUG``. """ # noqa: E501 return self._proxied.echo @echo.setter def echo(self, attr: Any) -> None: self._proxied.echo = attr # END PROXY METHODS AsyncEngine class AsyncTransaction( ProxyComparable[Transaction], StartableContext["AsyncTransaction"] ): """An asyncio proxy for a :class:`_engine.Transaction`.""" __slots__ = ("connection", "sync_transaction", "nested") sync_transaction: Optional[Transaction] connection: AsyncConnection nested: bool def __init__(self, connection: AsyncConnection, nested: bool = False): self.connection = connection self.sync_transaction = None self.nested = nested @classmethod def _regenerate_proxy_for_target( cls, target: Transaction ) -> AsyncTransaction: sync_connection = target.connection sync_transaction = target nested = isinstance(target, NestedTransaction) async_connection = AsyncConnection._retrieve_proxy_for_target( sync_connection ) assert async_connection is not None obj = cls.__new__(cls) obj.connection = async_connection obj.sync_transaction = obj._assign_proxied(sync_transaction) obj.nested = nested return obj @util.ro_non_memoized_property def _proxied(self) -> Transaction: if not self.sync_transaction: self._raise_for_not_started() return self.sync_transaction @property def is_valid(self) -> bool: return self._proxied.is_valid @property def is_active(self) -> bool: return self._proxied.is_active async def close(self) -> None: """Close this :class:`.AsyncTransaction`. If this transaction is the base transaction in a begin/commit nesting, the transaction will rollback(). Otherwise, the method returns. This is used to cancel a Transaction without affecting the scope of an enclosing transaction. """ await greenlet_spawn(self._proxied.close) async def rollback(self) -> None: """Roll back this :class:`.AsyncTransaction`.""" await greenlet_spawn(self._proxied.rollback) async def commit(self) -> None: """Commit this :class:`.AsyncTransaction`.""" await greenlet_spawn(self._proxied.commit) async def start(self, is_ctxmanager: bool = False) -> AsyncTransaction: """Start this :class:`_asyncio.AsyncTransaction` object's context outside of using a Python ``with:`` block. """ self.sync_transaction = self._assign_proxied( await greenlet_spawn( self.connection._proxied.begin_nested if self.nested else self.connection._proxied.begin ) ) if is_ctxmanager: self.sync_transaction.__enter__() return self async def __aexit__(self, type_: Any, value: Any, traceback: Any) -> None: await greenlet_spawn(self._proxied.__exit__, type_, value, traceback) @overload def _get_sync_engine_or_connection(async_engine: AsyncEngine) -> Engine: ... @overload def _get_sync_engine_or_connection( async_engine: AsyncConnection, ) -> Connection: ... def _get_sync_engine_or_connection( async_engine: Union[AsyncEngine, AsyncConnection] ) -> Union[Engine, Connection]: if isinstance(async_engine, AsyncConnection): return async_engine._proxied try: return async_engine.sync_engine except AttributeError as e: raise exc.ArgumentError( "AsyncEngine expected, got %r" % async_engine ) from e @inspection._inspects(AsyncConnection) def _no_insp_for_async_conn_yet( subject: AsyncConnection, # noqa: U100 ) -> NoReturn: raise exc.NoInspectionAvailable( "Inspection on an AsyncConnection is currently not supported. " "Please use ``run_sync`` to pass a callable where it's possible " "to call ``inspect`` on the passed connection.", code="xd3s", ) @inspection._inspects(AsyncEngine) def _no_insp_for_async_engine_xyet( subject: AsyncEngine, # noqa: U100 ) -> NoReturn: raise exc.NoInspectionAvailable( "Inspection on an AsyncEngine is currently not supported. " "Please obtain a connection then use ``conn.run_sync`` to pass a " "callable where it's possible to call ``inspect`` on the " "passed connection.", code="xd3s", )