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# ext/asyncio/engine.py
# Copyright (C) 2020-2024 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
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",
)