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# orm/scoping.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
from __future__ import annotations
from typing import Any
from typing import Callable
from typing import Dict
from typing import Generic
from typing import Iterable
from typing import Iterator
from typing import Optional
from typing import overload
from typing import Sequence
from typing import Tuple
from typing import Type
from typing import TYPE_CHECKING
from typing import TypeVar
from typing import Union
from .session import _S
from .session import Session
from .. import exc as sa_exc
from .. import util
from ..util import create_proxy_methods
from ..util import ScopedRegistry
from ..util import ThreadLocalRegistry
from ..util import warn
from ..util import warn_deprecated
from ..util.typing import Protocol
if TYPE_CHECKING:
from ._typing import _EntityType
from ._typing import _IdentityKeyType
from ._typing import OrmExecuteOptionsParameter
from .identity import IdentityMap
from .interfaces import ORMOption
from .mapper import Mapper
from .query import Query
from .query import RowReturningQuery
from .session import _BindArguments
from .session import _EntityBindKey
from .session import _PKIdentityArgument
from .session import _SessionBind
from .session import sessionmaker
from .session import SessionTransaction
from ..engine import Connection
from ..engine import CursorResult
from ..engine import Engine
from ..engine import Result
from ..engine import Row
from ..engine import RowMapping
from ..engine.interfaces import _CoreAnyExecuteParams
from ..engine.interfaces import _CoreSingleExecuteParams
from ..engine.interfaces import CoreExecuteOptionsParameter
from ..engine.result import ScalarResult
from ..sql._typing import _ColumnsClauseArgument
from ..sql._typing import _T0
from ..sql._typing import _T1
from ..sql._typing import _T2
from ..sql._typing import _T3
from ..sql._typing import _T4
from ..sql._typing import _T5
from ..sql._typing import _T6
from ..sql._typing import _T7
from ..sql._typing import _TypedColumnClauseArgument as _TCCA
from ..sql.base import Executable
from ..sql.dml import UpdateBase
from ..sql.elements import ClauseElement
from ..sql.roles import TypedColumnsClauseRole
from ..sql.selectable import ForUpdateParameter
from ..sql.selectable import TypedReturnsRows
_T = TypeVar("_T", bound=Any)
class QueryPropertyDescriptor(Protocol):
"""Describes the type applied to a class-level
:meth:`_orm.scoped_session.query_property` attribute.
.. versionadded:: 2.0.5
"""
def __get__(self, instance: Any, owner: Type[_T]) -> Query[_T]: ...
_O = TypeVar("_O", bound=object)
__all__ = ["scoped_session"]
@create_proxy_methods(
Session,
":class:`_orm.Session`",
":class:`_orm.scoping.scoped_session`",
classmethods=["close_all", "object_session", "identity_key"],
methods=[
"__contains__",
"__iter__",
"add",
"add_all",
"begin",
"begin_nested",
"close",
"reset",
"commit",
"connection",
"delete",
"execute",
"expire",
"expire_all",
"expunge",
"expunge_all",
"flush",
"get",
"get_one",
"get_bind",
"is_modified",
"bulk_save_objects",
"bulk_insert_mappings",
"bulk_update_mappings",
"merge",
"query",
"refresh",
"rollback",
"scalar",
"scalars",
],
attributes=[
"bind",
"dirty",
"deleted",
"new",
"identity_map",
"is_active",
"autoflush",
"no_autoflush",
"info",
],
)
class scoped_session(Generic[_S]):
"""Provides scoped management of :class:`.Session` objects.
See :ref:`unitofwork_contextual` for a tutorial.
.. note::
When using :ref:`asyncio_toplevel`, the async-compatible
:class:`_asyncio.async_scoped_session` class should be
used in place of :class:`.scoped_session`.
"""
_support_async: bool = False
session_factory: sessionmaker[_S]
"""The `session_factory` provided to `__init__` is stored in this
attribute and may be accessed at a later time. This can be useful when
a new non-scoped :class:`.Session` is needed."""
registry: ScopedRegistry[_S]
def __init__(
self,
session_factory: sessionmaker[_S],
scopefunc: Optional[Callable[[], Any]] = None,
):
"""Construct a new :class:`.scoped_session`.
:param session_factory: a factory to create new :class:`.Session`
instances. This is usually, but not necessarily, an instance
of :class:`.sessionmaker`.
:param scopefunc: optional function which defines
the current scope. If not passed, the :class:`.scoped_session`
object assumes "thread-local" scope, and will use
a Python ``threading.local()`` in order to maintain the current
:class:`.Session`. If passed, the function should return
a hashable token; this token will be used as the key in a
dictionary in order to store and retrieve the current
:class:`.Session`.
"""
self.session_factory = session_factory
if scopefunc:
self.registry = ScopedRegistry(session_factory, scopefunc)
else:
self.registry = ThreadLocalRegistry(session_factory)
@property
def _proxied(self) -> _S:
return self.registry()
def __call__(self, **kw: Any) -> _S:
r"""Return the current :class:`.Session`, creating it
using the :attr:`.scoped_session.session_factory` if not present.
:param \**kw: Keyword arguments will be passed to the
:attr:`.scoped_session.session_factory` callable, if an existing
:class:`.Session` is not present. If the :class:`.Session` is present
and keyword arguments have been passed,
:exc:`~sqlalchemy.exc.InvalidRequestError` is raised.
"""
if kw:
if self.registry.has():
raise sa_exc.InvalidRequestError(
"Scoped session is already present; "
"no new arguments may be specified."
)
else:
sess = self.session_factory(**kw)
self.registry.set(sess)
else:
sess = self.registry()
if not self._support_async and sess._is_asyncio:
warn_deprecated(
"Using `scoped_session` with asyncio is deprecated and "
"will raise an error in a future version. "
"Please use `async_scoped_session` instead.",
"1.4.23",
)
return sess
def configure(self, **kwargs: Any) -> None:
"""reconfigure the :class:`.sessionmaker` used by this
:class:`.scoped_session`.
See :meth:`.sessionmaker.configure`.
"""
if self.registry.has():
warn(
"At least one scoped session is already present. "
" configure() can not affect sessions that have "
"already been created."
)
self.session_factory.configure(**kwargs)
def remove(self) -> None:
"""Dispose of the current :class:`.Session`, if present.
This will first call :meth:`.Session.close` method
on the current :class:`.Session`, which releases any existing
transactional/connection resources still being held; transactions
specifically are rolled back. The :class:`.Session` is then
discarded. Upon next usage within the same scope,
the :class:`.scoped_session` will produce a new
:class:`.Session` object.
"""
if self.registry.has():
self.registry().close()
self.registry.clear()
def query_property(
self, query_cls: Optional[Type[Query[_T]]] = None
) -> QueryPropertyDescriptor:
"""return a class property which produces a legacy
:class:`_query.Query` object against the class and the current
:class:`.Session` when called.
.. legacy:: The :meth:`_orm.scoped_session.query_property` accessor
is specific to the legacy :class:`.Query` object and is not
considered to be part of :term:`2.0-style` ORM use.
e.g.::
from sqlalchemy.orm import QueryPropertyDescriptor
from sqlalchemy.orm import scoped_session
from sqlalchemy.orm import sessionmaker
Session = scoped_session(sessionmaker())
class MyClass:
query: QueryPropertyDescriptor = Session.query_property()
# after mappers are defined
result = MyClass.query.filter(MyClass.name=='foo').all()
Produces instances of the session's configured query class by
default. To override and use a custom implementation, provide
a ``query_cls`` callable. The callable will be invoked with
the class's mapper as a positional argument and a session
keyword argument.
There is no limit to the number of query properties placed on
a class.
"""
class query:
def __get__(s, instance: Any, owner: Type[_O]) -> Query[_O]:
if query_cls:
# custom query class
return query_cls(owner, session=self.registry()) # type: ignore # noqa: E501
else:
# session's configured query class
return self.registry().query(owner)
return query()
# START PROXY METHODS scoped_session
# code within this block is **programmatically,
# statically generated** by tools/generate_proxy_methods.py
def __contains__(self, instance: object) -> bool:
r"""Return True if the instance is associated with this session.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
The instance may be pending or persistent within the Session for a
result of True.
""" # noqa: E501
return self._proxied.__contains__(instance)
def __iter__(self) -> Iterator[object]:
r"""Iterate over all pending or persistent instances within this
Session.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
""" # noqa: E501
return self._proxied.__iter__()
def add(self, instance: object, _warn: bool = True) -> None:
r"""Place an object into this :class:`_orm.Session`.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Objects that are in the :term:`transient` state when passed to the
:meth:`_orm.Session.add` method will move to the
:term:`pending` state, until the next flush, at which point they
will move to the :term:`persistent` state.
Objects that are in the :term:`detached` state when passed to the
:meth:`_orm.Session.add` method will move to the :term:`persistent`
state directly.
If the transaction used by the :class:`_orm.Session` is rolled back,
objects which were transient when they were passed to
:meth:`_orm.Session.add` will be moved back to the
:term:`transient` state, and will no longer be present within this
:class:`_orm.Session`.
.. seealso::
:meth:`_orm.Session.add_all`
:ref:`session_adding` - at :ref:`session_basics`
""" # noqa: E501
return self._proxied.add(instance, _warn=_warn)
def add_all(self, instances: Iterable[object]) -> None:
r"""Add the given collection of instances to this :class:`_orm.Session`.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
See the documentation for :meth:`_orm.Session.add` for a general
behavioral description.
.. seealso::
:meth:`_orm.Session.add`
:ref:`session_adding` - at :ref:`session_basics`
""" # noqa: E501
return self._proxied.add_all(instances)
def begin(self, nested: bool = False) -> SessionTransaction:
r"""Begin a transaction, or nested transaction,
on this :class:`.Session`, if one is not already begun.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
The :class:`_orm.Session` object features **autobegin** behavior,
so that normally it is not necessary to call the
:meth:`_orm.Session.begin`
method explicitly. However, it may be used in order to control
the scope of when the transactional state is begun.
When used to begin the outermost transaction, an error is raised
if this :class:`.Session` is already inside of a transaction.
:param nested: if True, begins a SAVEPOINT transaction and is
equivalent to calling :meth:`~.Session.begin_nested`. For
documentation on SAVEPOINT transactions, please see
:ref:`session_begin_nested`.
:return: the :class:`.SessionTransaction` object. Note that
:class:`.SessionTransaction`
acts as a Python context manager, allowing :meth:`.Session.begin`
to be used in a "with" block. See :ref:`session_explicit_begin` for
an example.
.. seealso::
:ref:`session_autobegin`
:ref:`unitofwork_transaction`
:meth:`.Session.begin_nested`
""" # noqa: E501
return self._proxied.begin(nested=nested)
def begin_nested(self) -> SessionTransaction:
r"""Begin a "nested" transaction on this Session, e.g. SAVEPOINT.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
The target database(s) and associated drivers must support SQL
SAVEPOINT for this method to function correctly.
For documentation on SAVEPOINT
transactions, please see :ref:`session_begin_nested`.
:return: the :class:`.SessionTransaction` object. Note that
:class:`.SessionTransaction` acts as a context manager, allowing
:meth:`.Session.begin_nested` to be used in a "with" block.
See :ref:`session_begin_nested` for a usage example.
.. seealso::
:ref:`session_begin_nested`
:ref:`pysqlite_serializable` - special workarounds required
with the SQLite driver in order for SAVEPOINT to work
correctly. For asyncio use cases, see the section
:ref:`aiosqlite_serializable`.
""" # noqa: E501
return self._proxied.begin_nested()
def close(self) -> None:
r"""Close out the transactional resources and ORM objects used by this
:class:`_orm.Session`.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This expunges all ORM objects associated with this
:class:`_orm.Session`, ends any transaction in progress and
:term:`releases` any :class:`_engine.Connection` objects which this
:class:`_orm.Session` itself has checked out from associated
:class:`_engine.Engine` objects. The operation then leaves the
:class:`_orm.Session` in a state which it may be used again.
.. tip::
In the default running mode the :meth:`_orm.Session.close`
method **does not prevent the Session from being used again**.
The :class:`_orm.Session` itself does not actually have a
distinct "closed" state; it merely means
the :class:`_orm.Session` will release all database connections
and ORM objects.
Setting the parameter :paramref:`_orm.Session.close_resets_only`
to ``False`` will instead make the ``close`` final, meaning that
any further action on the session will be forbidden.
.. versionchanged:: 1.4 The :meth:`.Session.close` method does not
immediately create a new :class:`.SessionTransaction` object;
instead, the new :class:`.SessionTransaction` is created only if
the :class:`.Session` is used again for a database operation.
.. seealso::
:ref:`session_closing` - detail on the semantics of
:meth:`_orm.Session.close` and :meth:`_orm.Session.reset`.
:meth:`_orm.Session.reset` - a similar method that behaves like
``close()`` with the parameter
:paramref:`_orm.Session.close_resets_only` set to ``True``.
""" # noqa: E501
return self._proxied.close()
def reset(self) -> None:
r"""Close out the transactional resources and ORM objects used by this
:class:`_orm.Session`, resetting the session to its initial state.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This method provides for same "reset-only" behavior that the
:meth:`_orm.Session.close` method has provided historically, where the
state of the :class:`_orm.Session` is reset as though the object were
brand new, and ready to be used again.
This method may then be useful for :class:`_orm.Session` objects
which set :paramref:`_orm.Session.close_resets_only` to ``False``,
so that "reset only" behavior is still available.
.. versionadded:: 2.0.22
.. seealso::
:ref:`session_closing` - detail on the semantics of
:meth:`_orm.Session.close` and :meth:`_orm.Session.reset`.
:meth:`_orm.Session.close` - a similar method will additionally
prevent re-use of the Session when the parameter
:paramref:`_orm.Session.close_resets_only` is set to ``False``.
""" # noqa: E501
return self._proxied.reset()
def commit(self) -> None:
r"""Flush pending changes and commit the current transaction.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
When the COMMIT operation is complete, all objects are fully
:term:`expired`, erasing their internal contents, which will be
automatically re-loaded when the objects are next accessed. In the
interim, these objects are in an expired state and will not function if
they are :term:`detached` from the :class:`.Session`. Additionally,
this re-load operation is not supported when using asyncio-oriented
APIs. The :paramref:`.Session.expire_on_commit` parameter may be used
to disable this behavior.
When there is no transaction in place for the :class:`.Session`,
indicating that no operations were invoked on this :class:`.Session`
since the previous call to :meth:`.Session.commit`, the method will
begin and commit an internal-only "logical" transaction, that does not
normally affect the database unless pending flush changes were
detected, but will still invoke event handlers and object expiration
rules.
The outermost database transaction is committed unconditionally,
automatically releasing any SAVEPOINTs in effect.
.. seealso::
:ref:`session_committing`
:ref:`unitofwork_transaction`
:ref:`asyncio_orm_avoid_lazyloads`
""" # noqa: E501
return self._proxied.commit()
def connection(
self,
bind_arguments: Optional[_BindArguments] = None,
execution_options: Optional[CoreExecuteOptionsParameter] = None,
) -> Connection:
r"""Return a :class:`_engine.Connection` object corresponding to this
:class:`.Session` object's transactional state.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Either the :class:`_engine.Connection` corresponding to the current
transaction is returned, or if no transaction is in progress, a new
one is begun and the :class:`_engine.Connection`
returned (note that no
transactional state is established with the DBAPI until the first
SQL statement is emitted).
Ambiguity in multi-bind or unbound :class:`.Session` objects can be
resolved through any of the optional keyword arguments. This
ultimately makes usage of the :meth:`.get_bind` method for resolution.
:param bind_arguments: dictionary of bind arguments. May include
"mapper", "bind", "clause", other custom arguments that are passed
to :meth:`.Session.get_bind`.
:param execution_options: a dictionary of execution options that will
be passed to :meth:`_engine.Connection.execution_options`, **when the
connection is first procured only**. If the connection is already
present within the :class:`.Session`, a warning is emitted and
the arguments are ignored.
.. seealso::
:ref:`session_transaction_isolation`
""" # noqa: E501
return self._proxied.connection(
bind_arguments=bind_arguments, execution_options=execution_options
)
def delete(self, instance: object) -> None:
r"""Mark an instance as deleted.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
The object is assumed to be either :term:`persistent` or
:term:`detached` when passed; after the method is called, the
object will remain in the :term:`persistent` state until the next
flush proceeds. During this time, the object will also be a member
of the :attr:`_orm.Session.deleted` collection.
When the next flush proceeds, the object will move to the
:term:`deleted` state, indicating a ``DELETE`` statement was emitted
for its row within the current transaction. When the transaction
is successfully committed,
the deleted object is moved to the :term:`detached` state and is
no longer present within this :class:`_orm.Session`.
.. seealso::
:ref:`session_deleting` - at :ref:`session_basics`
""" # noqa: E501
return self._proxied.delete(instance)
@overload
def execute(
self,
statement: TypedReturnsRows[_T],
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
_parent_execute_state: Optional[Any] = None,
_add_event: Optional[Any] = None,
) -> Result[_T]: ...
@overload
def execute(
self,
statement: UpdateBase,
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
_parent_execute_state: Optional[Any] = None,
_add_event: Optional[Any] = None,
) -> CursorResult[Any]: ...
@overload
def execute(
self,
statement: Executable,
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
_parent_execute_state: Optional[Any] = None,
_add_event: Optional[Any] = None,
) -> Result[Any]: ...
def execute(
self,
statement: Executable,
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
_parent_execute_state: Optional[Any] = None,
_add_event: Optional[Any] = None,
) -> Result[Any]:
r"""Execute a SQL expression construct.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Returns a :class:`_engine.Result` object representing
results of the statement execution.
E.g.::
from sqlalchemy import select
result = session.execute(
select(User).where(User.id == 5)
)
The API contract of :meth:`_orm.Session.execute` is similar to that
of :meth:`_engine.Connection.execute`, the :term:`2.0 style` version
of :class:`_engine.Connection`.
.. versionchanged:: 1.4 the :meth:`_orm.Session.execute` method is
now the primary point of ORM statement execution when using
:term:`2.0 style` ORM usage.
:param statement:
An executable statement (i.e. an :class:`.Executable` expression
such as :func:`_expression.select`).
:param params:
Optional dictionary, or list of dictionaries, containing
bound parameter values. If a single dictionary, single-row
execution occurs; if a list of dictionaries, an
"executemany" will be invoked. The keys in each dictionary
must correspond to parameter names present in the statement.
: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`, and may also
provide additional options understood only in an ORM context.
.. seealso::
:ref:`orm_queryguide_execution_options` - ORM-specific execution
options
:param bind_arguments: dictionary of additional arguments to determine
the bind. May include "mapper", "bind", or other custom arguments.
Contents of this dictionary are passed to the
:meth:`.Session.get_bind` method.
:return: a :class:`_engine.Result` object.
""" # noqa: E501
return self._proxied.execute(
statement,
params=params,
execution_options=execution_options,
bind_arguments=bind_arguments,
_parent_execute_state=_parent_execute_state,
_add_event=_add_event,
)
def expire(
self, instance: object, attribute_names: Optional[Iterable[str]] = None
) -> None:
r"""Expire the attributes on an instance.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Marks the attributes of an instance as out of date. When an expired
attribute is next accessed, a query will be issued to the
:class:`.Session` object's current transactional context in order to
load all expired attributes for the given instance. Note that
a highly isolated transaction will return the same values as were
previously read in that same transaction, regardless of changes
in database state outside of that transaction.
To expire all objects in the :class:`.Session` simultaneously,
use :meth:`Session.expire_all`.
The :class:`.Session` object's default behavior is to
expire all state whenever the :meth:`Session.rollback`
or :meth:`Session.commit` methods are called, so that new
state can be loaded for the new transaction. For this reason,
calling :meth:`Session.expire` only makes sense for the specific
case that a non-ORM SQL statement was emitted in the current
transaction.
:param instance: The instance to be refreshed.
:param attribute_names: optional list of string attribute names
indicating a subset of attributes to be expired.
.. seealso::
:ref:`session_expire` - introductory material
:meth:`.Session.expire`
:meth:`.Session.refresh`
:meth:`_orm.Query.populate_existing`
""" # noqa: E501
return self._proxied.expire(instance, attribute_names=attribute_names)
def expire_all(self) -> None:
r"""Expires all persistent instances within this Session.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
When any attributes on a persistent instance is next accessed,
a query will be issued using the
:class:`.Session` object's current transactional context in order to
load all expired attributes for the given instance. Note that
a highly isolated transaction will return the same values as were
previously read in that same transaction, regardless of changes
in database state outside of that transaction.
To expire individual objects and individual attributes
on those objects, use :meth:`Session.expire`.
The :class:`.Session` object's default behavior is to
expire all state whenever the :meth:`Session.rollback`
or :meth:`Session.commit` methods are called, so that new
state can be loaded for the new transaction. For this reason,
calling :meth:`Session.expire_all` is not usually needed,
assuming the transaction is isolated.
.. seealso::
:ref:`session_expire` - introductory material
:meth:`.Session.expire`
:meth:`.Session.refresh`
:meth:`_orm.Query.populate_existing`
""" # noqa: E501
return self._proxied.expire_all()
def expunge(self, instance: object) -> None:
r"""Remove the `instance` from this ``Session``.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This will free all internal references to the instance. Cascading
will be applied according to the *expunge* cascade rule.
""" # noqa: E501
return self._proxied.expunge(instance)
def expunge_all(self) -> None:
r"""Remove all object instances from this ``Session``.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This is equivalent to calling ``expunge(obj)`` on all objects in this
``Session``.
""" # noqa: E501
return self._proxied.expunge_all()
def flush(self, objects: Optional[Sequence[Any]] = None) -> None:
r"""Flush all the object changes to the database.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Writes out all pending object creations, deletions and modifications
to the database as INSERTs, DELETEs, UPDATEs, etc. Operations are
automatically ordered by the Session's unit of work dependency
solver.
Database operations will be issued in the current transactional
context and do not affect the state of the transaction, unless an
error occurs, in which case the entire transaction is rolled back.
You may flush() as often as you like within a transaction to move
changes from Python to the database's transaction buffer.
:param objects: Optional; restricts the flush operation to operate
only on elements that are in the given collection.
This feature is for an extremely narrow set of use cases where
particular objects may need to be operated upon before the
full flush() occurs. It is not intended for general use.
""" # noqa: E501
return self._proxied.flush(objects=objects)
def get(
self,
entity: _EntityBindKey[_O],
ident: _PKIdentityArgument,
*,
options: Optional[Sequence[ORMOption]] = None,
populate_existing: bool = False,
with_for_update: ForUpdateParameter = None,
identity_token: Optional[Any] = None,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
) -> Optional[_O]:
r"""Return an instance based on the given primary key identifier,
or ``None`` if not found.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
E.g.::
my_user = session.get(User, 5)
some_object = session.get(VersionedFoo, (5, 10))
some_object = session.get(
VersionedFoo,
{"id": 5, "version_id": 10}
)
.. versionadded:: 1.4 Added :meth:`_orm.Session.get`, which is moved
from the now legacy :meth:`_orm.Query.get` method.
:meth:`_orm.Session.get` is special in that it provides direct
access to the identity map of the :class:`.Session`.
If the given primary key identifier is present
in the local identity map, the object is returned
directly from this collection and no SQL is emitted,
unless the object has been marked fully expired.
If not present,
a SELECT is performed in order to locate the object.
:meth:`_orm.Session.get` also will perform a check if
the object is present in the identity map and
marked as expired - a SELECT
is emitted to refresh the object as well as to
ensure that the row is still present.
If not, :class:`~sqlalchemy.orm.exc.ObjectDeletedError` is raised.
:param entity: a mapped class or :class:`.Mapper` indicating the
type of entity to be loaded.
:param ident: A scalar, tuple, or dictionary representing the
primary key. For a composite (e.g. multiple column) primary key,
a tuple or dictionary should be passed.
For a single-column primary key, the scalar calling form is typically
the most expedient. If the primary key of a row is the value "5",
the call looks like::
my_object = session.get(SomeClass, 5)
The tuple form contains primary key values typically in
the order in which they correspond to the mapped
:class:`_schema.Table`
object's primary key columns, or if the
:paramref:`_orm.Mapper.primary_key` configuration parameter were
used, in
the order used for that parameter. For example, if the primary key
of a row is represented by the integer
digits "5, 10" the call would look like::
my_object = session.get(SomeClass, (5, 10))
The dictionary form should include as keys the mapped attribute names
corresponding to each element of the primary key. If the mapped class
has the attributes ``id``, ``version_id`` as the attributes which
store the object's primary key value, the call would look like::
my_object = session.get(SomeClass, {"id": 5, "version_id": 10})
:param options: optional sequence of loader options which will be
applied to the query, if one is emitted.
:param populate_existing: causes the method to unconditionally emit
a SQL query and refresh the object with the newly loaded data,
regardless of whether or not the object is already present.
:param with_for_update: optional boolean ``True`` indicating FOR UPDATE
should be used, or may be a dictionary containing flags to
indicate a more specific set of FOR UPDATE flags for the SELECT;
flags should match the parameters of
:meth:`_query.Query.with_for_update`.
Supersedes the :paramref:`.Session.refresh.lockmode` parameter.
:param execution_options: optional dictionary of execution options,
which will be associated with the query execution if one is emitted.
This dictionary can provide a subset of the options that are
accepted by :meth:`_engine.Connection.execution_options`, and may
also provide additional options understood only in an ORM context.
.. versionadded:: 1.4.29
.. seealso::
:ref:`orm_queryguide_execution_options` - ORM-specific execution
options
:param bind_arguments: dictionary of additional arguments to determine
the bind. May include "mapper", "bind", or other custom arguments.
Contents of this dictionary are passed to the
:meth:`.Session.get_bind` method.
.. versionadded: 2.0.0rc1
:return: The object instance, or ``None``.
""" # noqa: E501
return self._proxied.get(
entity,
ident,
options=options,
populate_existing=populate_existing,
with_for_update=with_for_update,
identity_token=identity_token,
execution_options=execution_options,
bind_arguments=bind_arguments,
)
def get_one(
self,
entity: _EntityBindKey[_O],
ident: _PKIdentityArgument,
*,
options: Optional[Sequence[ORMOption]] = None,
populate_existing: bool = False,
with_for_update: ForUpdateParameter = None,
identity_token: Optional[Any] = None,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
) -> _O:
r"""Return exactly one instance based on the given primary key
identifier, or raise an exception if not found.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Raises ``sqlalchemy.orm.exc.NoResultFound`` if the query
selects no rows.
For a detailed documentation of the arguments see the
method :meth:`.Session.get`.
.. versionadded:: 2.0.22
:return: The object instance.
.. seealso::
:meth:`.Session.get` - equivalent method that instead
returns ``None`` if no row was found with the provided primary
key
""" # noqa: E501
return self._proxied.get_one(
entity,
ident,
options=options,
populate_existing=populate_existing,
with_for_update=with_for_update,
identity_token=identity_token,
execution_options=execution_options,
bind_arguments=bind_arguments,
)
def get_bind(
self,
mapper: Optional[_EntityBindKey[_O]] = None,
*,
clause: Optional[ClauseElement] = None,
bind: Optional[_SessionBind] = None,
_sa_skip_events: Optional[bool] = None,
_sa_skip_for_implicit_returning: bool = False,
**kw: Any,
) -> Union[Engine, Connection]:
r"""Return a "bind" to which this :class:`.Session` is bound.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
The "bind" is usually an instance of :class:`_engine.Engine`,
except in the case where the :class:`.Session` has been
explicitly bound directly to a :class:`_engine.Connection`.
For a multiply-bound or unbound :class:`.Session`, the
``mapper`` or ``clause`` arguments are used to determine the
appropriate bind to return.
Note that the "mapper" argument is usually present
when :meth:`.Session.get_bind` is called via an ORM
operation such as a :meth:`.Session.query`, each
individual INSERT/UPDATE/DELETE operation within a
:meth:`.Session.flush`, call, etc.
The order of resolution is:
1. if mapper given and :paramref:`.Session.binds` is present,
locate a bind based first on the mapper in use, then
on the mapped class in use, then on any base classes that are
present in the ``__mro__`` of the mapped class, from more specific
superclasses to more general.
2. if clause given and ``Session.binds`` is present,
locate a bind based on :class:`_schema.Table` objects
found in the given clause present in ``Session.binds``.
3. if ``Session.binds`` is present, return that.
4. if clause given, attempt to return a bind
linked to the :class:`_schema.MetaData` ultimately
associated with the clause.
5. if mapper given, attempt to return a bind
linked to the :class:`_schema.MetaData` ultimately
associated with the :class:`_schema.Table` or other
selectable to which the mapper is mapped.
6. No bind can be found, :exc:`~sqlalchemy.exc.UnboundExecutionError`
is raised.
Note that the :meth:`.Session.get_bind` method can be overridden on
a user-defined subclass of :class:`.Session` to provide any kind
of bind resolution scheme. See the example at
:ref:`session_custom_partitioning`.
:param mapper:
Optional mapped class or corresponding :class:`_orm.Mapper` instance.
The bind can be derived from a :class:`_orm.Mapper` first by
consulting the "binds" map associated with this :class:`.Session`,
and secondly by consulting the :class:`_schema.MetaData` associated
with the :class:`_schema.Table` to which the :class:`_orm.Mapper` is
mapped for a bind.
:param clause:
A :class:`_expression.ClauseElement` (i.e.
:func:`_expression.select`,
:func:`_expression.text`,
etc.). If the ``mapper`` argument is not present or could not
produce a bind, the given expression construct will be searched
for a bound element, typically a :class:`_schema.Table`
associated with
bound :class:`_schema.MetaData`.
.. seealso::
:ref:`session_partitioning`
:paramref:`.Session.binds`
:meth:`.Session.bind_mapper`
:meth:`.Session.bind_table`
""" # noqa: E501
return self._proxied.get_bind(
mapper=mapper,
clause=clause,
bind=bind,
_sa_skip_events=_sa_skip_events,
_sa_skip_for_implicit_returning=_sa_skip_for_implicit_returning,
**kw,
)
def is_modified(
self, instance: object, include_collections: bool = True
) -> bool:
r"""Return ``True`` if the given instance has locally
modified attributes.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This method retrieves the history for each instrumented
attribute on the instance and performs a comparison of the current
value to its previously flushed or committed value, if any.
It is in effect a more expensive and accurate
version of checking for the given instance in the
:attr:`.Session.dirty` collection; a full test for
each attribute's net "dirty" status is performed.
E.g.::
return session.is_modified(someobject)
A few caveats to this method apply:
* Instances present in the :attr:`.Session.dirty` collection may
report ``False`` when tested with this method. This is because
the object may have received change events via attribute mutation,
thus placing it in :attr:`.Session.dirty`, but ultimately the state
is the same as that loaded from the database, resulting in no net
change here.
* Scalar attributes may not have recorded the previously set
value when a new value was applied, if the attribute was not loaded,
or was expired, at the time the new value was received - in these
cases, the attribute is assumed to have a change, even if there is
ultimately no net change against its database value. SQLAlchemy in
most cases does not need the "old" value when a set event occurs, so
it skips the expense of a SQL call if the old value isn't present,
based on the assumption that an UPDATE of the scalar value is
usually needed, and in those few cases where it isn't, is less
expensive on average than issuing a defensive SELECT.
The "old" value is fetched unconditionally upon set only if the
attribute container has the ``active_history`` flag set to ``True``.
This flag is set typically for primary key attributes and scalar
object references that are not a simple many-to-one. To set this
flag for any arbitrary mapped column, use the ``active_history``
argument with :func:`.column_property`.
:param instance: mapped instance to be tested for pending changes.
:param include_collections: Indicates if multivalued collections
should be included in the operation. Setting this to ``False`` is a
way to detect only local-column based properties (i.e. scalar columns
or many-to-one foreign keys) that would result in an UPDATE for this
instance upon flush.
""" # noqa: E501
return self._proxied.is_modified(
instance, include_collections=include_collections
)
def bulk_save_objects(
self,
objects: Iterable[object],
return_defaults: bool = False,
update_changed_only: bool = True,
preserve_order: bool = True,
) -> None:
r"""Perform a bulk save of the given list of objects.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
.. legacy::
This method is a legacy feature as of the 2.0 series of
SQLAlchemy. For modern bulk INSERT and UPDATE, see
the sections :ref:`orm_queryguide_bulk_insert` and
:ref:`orm_queryguide_bulk_update`.
For general INSERT and UPDATE of existing ORM mapped objects,
prefer standard :term:`unit of work` data management patterns,
introduced in the :ref:`unified_tutorial` at
:ref:`tutorial_orm_data_manipulation`. SQLAlchemy 2.0
now uses :ref:`engine_insertmanyvalues` with modern dialects
which solves previous issues of bulk INSERT slowness.
:param objects: a sequence of mapped object instances. The mapped
objects are persisted as is, and are **not** associated with the
:class:`.Session` afterwards.
For each object, whether the object is sent as an INSERT or an
UPDATE is dependent on the same rules used by the :class:`.Session`
in traditional operation; if the object has the
:attr:`.InstanceState.key`
attribute set, then the object is assumed to be "detached" and
will result in an UPDATE. Otherwise, an INSERT is used.
In the case of an UPDATE, statements are grouped based on which
attributes have changed, and are thus to be the subject of each
SET clause. If ``update_changed_only`` is False, then all
attributes present within each object are applied to the UPDATE
statement, which may help in allowing the statements to be grouped
together into a larger executemany(), and will also reduce the
overhead of checking history on attributes.
:param return_defaults: when True, rows that are missing values which
generate defaults, namely integer primary key defaults and sequences,
will be inserted **one at a time**, so that the primary key value
is available. In particular this will allow joined-inheritance
and other multi-table mappings to insert correctly without the need
to provide primary key values ahead of time; however,
:paramref:`.Session.bulk_save_objects.return_defaults` **greatly
reduces the performance gains** of the method overall. It is strongly
advised to please use the standard :meth:`_orm.Session.add_all`
approach.
:param update_changed_only: when True, UPDATE statements are rendered
based on those attributes in each state that have logged changes.
When False, all attributes present are rendered into the SET clause
with the exception of primary key attributes.
:param preserve_order: when True, the order of inserts and updates
matches exactly the order in which the objects are given. When
False, common types of objects are grouped into inserts
and updates, to allow for more batching opportunities.
.. seealso::
:doc:`queryguide/dml`
:meth:`.Session.bulk_insert_mappings`
:meth:`.Session.bulk_update_mappings`
""" # noqa: E501
return self._proxied.bulk_save_objects(
objects,
return_defaults=return_defaults,
update_changed_only=update_changed_only,
preserve_order=preserve_order,
)
def bulk_insert_mappings(
self,
mapper: Mapper[Any],
mappings: Iterable[Dict[str, Any]],
return_defaults: bool = False,
render_nulls: bool = False,
) -> None:
r"""Perform a bulk insert of the given list of mapping dictionaries.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
.. legacy::
This method is a legacy feature as of the 2.0 series of
SQLAlchemy. For modern bulk INSERT and UPDATE, see
the sections :ref:`orm_queryguide_bulk_insert` and
:ref:`orm_queryguide_bulk_update`. The 2.0 API shares
implementation details with this method and adds new features
as well.
:param mapper: a mapped class, or the actual :class:`_orm.Mapper`
object,
representing the single kind of object represented within the mapping
list.
:param mappings: a sequence of dictionaries, each one containing the
state of the mapped row to be inserted, in terms of the attribute
names on the mapped class. If the mapping refers to multiple tables,
such as a joined-inheritance mapping, each dictionary must contain all
keys to be populated into all tables.
:param return_defaults: when True, the INSERT process will be altered
to ensure that newly generated primary key values will be fetched.
The rationale for this parameter is typically to enable
:ref:`Joined Table Inheritance <joined_inheritance>` mappings to
be bulk inserted.
.. note:: for backends that don't support RETURNING, the
:paramref:`_orm.Session.bulk_insert_mappings.return_defaults`
parameter can significantly decrease performance as INSERT
statements can no longer be batched. See
:ref:`engine_insertmanyvalues`
for background on which backends are affected.
:param render_nulls: When True, a value of ``None`` will result
in a NULL value being included in the INSERT statement, rather
than the column being omitted from the INSERT. This allows all
the rows being INSERTed to have the identical set of columns which
allows the full set of rows to be batched to the DBAPI. Normally,
each column-set that contains a different combination of NULL values
than the previous row must omit a different series of columns from
the rendered INSERT statement, which means it must be emitted as a
separate statement. By passing this flag, the full set of rows
are guaranteed to be batchable into one batch; the cost however is
that server-side defaults which are invoked by an omitted column will
be skipped, so care must be taken to ensure that these are not
necessary.
.. warning::
When this flag is set, **server side default SQL values will
not be invoked** for those columns that are inserted as NULL;
the NULL value will be sent explicitly. Care must be taken
to ensure that no server-side default functions need to be
invoked for the operation as a whole.
.. seealso::
:doc:`queryguide/dml`
:meth:`.Session.bulk_save_objects`
:meth:`.Session.bulk_update_mappings`
""" # noqa: E501
return self._proxied.bulk_insert_mappings(
mapper,
mappings,
return_defaults=return_defaults,
render_nulls=render_nulls,
)
def bulk_update_mappings(
self, mapper: Mapper[Any], mappings: Iterable[Dict[str, Any]]
) -> None:
r"""Perform a bulk update of the given list of mapping dictionaries.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
.. legacy::
This method is a legacy feature as of the 2.0 series of
SQLAlchemy. For modern bulk INSERT and UPDATE, see
the sections :ref:`orm_queryguide_bulk_insert` and
:ref:`orm_queryguide_bulk_update`. The 2.0 API shares
implementation details with this method and adds new features
as well.
:param mapper: a mapped class, or the actual :class:`_orm.Mapper`
object,
representing the single kind of object represented within the mapping
list.
:param mappings: a sequence of dictionaries, each one containing the
state of the mapped row to be updated, in terms of the attribute names
on the mapped class. If the mapping refers to multiple tables, such
as a joined-inheritance mapping, each dictionary may contain keys
corresponding to all tables. All those keys which are present and
are not part of the primary key are applied to the SET clause of the
UPDATE statement; the primary key values, which are required, are
applied to the WHERE clause.
.. seealso::
:doc:`queryguide/dml`
:meth:`.Session.bulk_insert_mappings`
:meth:`.Session.bulk_save_objects`
""" # noqa: E501
return self._proxied.bulk_update_mappings(mapper, mappings)
def merge(
self,
instance: _O,
*,
load: bool = True,
options: Optional[Sequence[ORMOption]] = None,
) -> _O:
r"""Copy the state of a given instance into a corresponding instance
within this :class:`.Session`.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
:meth:`.Session.merge` examines the primary key attributes of the
source instance, and attempts to reconcile it with an instance of the
same primary key in the session. If not found locally, it attempts
to load the object from the database based on primary key, and if
none can be located, creates a new instance. The state of each
attribute on the source instance is then copied to the target
instance. The resulting target instance is then returned by the
method; the original source instance is left unmodified, and
un-associated with the :class:`.Session` if not already.
This operation cascades to associated instances if the association is
mapped with ``cascade="merge"``.
See :ref:`unitofwork_merging` for a detailed discussion of merging.
:param instance: Instance to be merged.
:param load: Boolean, when False, :meth:`.merge` switches into
a "high performance" mode which causes it to forego emitting history
events as well as all database access. This flag is used for
cases such as transferring graphs of objects into a :class:`.Session`
from a second level cache, or to transfer just-loaded objects
into the :class:`.Session` owned by a worker thread or process
without re-querying the database.
The ``load=False`` use case adds the caveat that the given
object has to be in a "clean" state, that is, has no pending changes
to be flushed - even if the incoming object is detached from any
:class:`.Session`. This is so that when
the merge operation populates local attributes and
cascades to related objects and
collections, the values can be "stamped" onto the
target object as is, without generating any history or attribute
events, and without the need to reconcile the incoming data with
any existing related objects or collections that might not
be loaded. The resulting objects from ``load=False`` are always
produced as "clean", so it is only appropriate that the given objects
should be "clean" as well, else this suggests a mis-use of the
method.
:param options: optional sequence of loader options which will be
applied to the :meth:`_orm.Session.get` method when the merge
operation loads the existing version of the object from the database.
.. versionadded:: 1.4.24
.. seealso::
:func:`.make_transient_to_detached` - provides for an alternative
means of "merging" a single object into the :class:`.Session`
""" # noqa: E501
return self._proxied.merge(instance, load=load, options=options)
@overload
def query(self, _entity: _EntityType[_O]) -> Query[_O]: ...
@overload
def query(
self, _colexpr: TypedColumnsClauseRole[_T]
) -> RowReturningQuery[Tuple[_T]]: ...
# START OVERLOADED FUNCTIONS self.query RowReturningQuery 2-8
# code within this block is **programmatically,
# statically generated** by tools/generate_tuple_map_overloads.py
@overload
def query(
self, __ent0: _TCCA[_T0], __ent1: _TCCA[_T1]
) -> RowReturningQuery[Tuple[_T0, _T1]]: ...
@overload
def query(
self, __ent0: _TCCA[_T0], __ent1: _TCCA[_T1], __ent2: _TCCA[_T2]
) -> RowReturningQuery[Tuple[_T0, _T1, _T2]]: ...
@overload
def query(
self,
__ent0: _TCCA[_T0],
__ent1: _TCCA[_T1],
__ent2: _TCCA[_T2],
__ent3: _TCCA[_T3],
) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3]]: ...
@overload
def query(
self,
__ent0: _TCCA[_T0],
__ent1: _TCCA[_T1],
__ent2: _TCCA[_T2],
__ent3: _TCCA[_T3],
__ent4: _TCCA[_T4],
) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4]]: ...
@overload
def query(
self,
__ent0: _TCCA[_T0],
__ent1: _TCCA[_T1],
__ent2: _TCCA[_T2],
__ent3: _TCCA[_T3],
__ent4: _TCCA[_T4],
__ent5: _TCCA[_T5],
) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4, _T5]]: ...
@overload
def query(
self,
__ent0: _TCCA[_T0],
__ent1: _TCCA[_T1],
__ent2: _TCCA[_T2],
__ent3: _TCCA[_T3],
__ent4: _TCCA[_T4],
__ent5: _TCCA[_T5],
__ent6: _TCCA[_T6],
) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4, _T5, _T6]]: ...
@overload
def query(
self,
__ent0: _TCCA[_T0],
__ent1: _TCCA[_T1],
__ent2: _TCCA[_T2],
__ent3: _TCCA[_T3],
__ent4: _TCCA[_T4],
__ent5: _TCCA[_T5],
__ent6: _TCCA[_T6],
__ent7: _TCCA[_T7],
) -> RowReturningQuery[Tuple[_T0, _T1, _T2, _T3, _T4, _T5, _T6, _T7]]: ...
# END OVERLOADED FUNCTIONS self.query
@overload
def query(
self, *entities: _ColumnsClauseArgument[Any], **kwargs: Any
) -> Query[Any]: ...
def query(
self, *entities: _ColumnsClauseArgument[Any], **kwargs: Any
) -> Query[Any]:
r"""Return a new :class:`_query.Query` object corresponding to this
:class:`_orm.Session`.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Note that the :class:`_query.Query` object is legacy as of
SQLAlchemy 2.0; the :func:`_sql.select` construct is now used
to construct ORM queries.
.. seealso::
:ref:`unified_tutorial`
:ref:`queryguide_toplevel`
:ref:`query_api_toplevel` - legacy API doc
""" # noqa: E501
return self._proxied.query(*entities, **kwargs)
def refresh(
self,
instance: object,
attribute_names: Optional[Iterable[str]] = None,
with_for_update: ForUpdateParameter = None,
) -> None:
r"""Expire and refresh attributes on the given instance.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
The selected attributes will first be expired as they would when using
:meth:`_orm.Session.expire`; then a SELECT statement will be issued to
the database to refresh column-oriented attributes with the current
value available in the current transaction.
:func:`_orm.relationship` oriented attributes will also be immediately
loaded if they were already eagerly loaded on the object, using the
same eager loading strategy that they were loaded with originally.
.. versionadded:: 1.4 - the :meth:`_orm.Session.refresh` method
can also refresh eagerly loaded attributes.
:func:`_orm.relationship` oriented attributes that would normally
load using the ``select`` (or "lazy") loader strategy will also
load **if they are named explicitly in the attribute_names
collection**, emitting a SELECT statement for the attribute using the
``immediate`` loader strategy. If lazy-loaded relationships are not
named in :paramref:`_orm.Session.refresh.attribute_names`, then
they remain as "lazy loaded" attributes and are not implicitly
refreshed.
.. versionchanged:: 2.0.4 The :meth:`_orm.Session.refresh` method
will now refresh lazy-loaded :func:`_orm.relationship` oriented
attributes for those which are named explicitly in the
:paramref:`_orm.Session.refresh.attribute_names` collection.
.. tip::
While the :meth:`_orm.Session.refresh` method is capable of
refreshing both column and relationship oriented attributes, its
primary focus is on refreshing of local column-oriented attributes
on a single instance. For more open ended "refresh" functionality,
including the ability to refresh the attributes on many objects at
once while having explicit control over relationship loader
strategies, use the
:ref:`populate existing <orm_queryguide_populate_existing>` feature
instead.
Note that a highly isolated transaction will return the same values as
were previously read in that same transaction, regardless of changes
in database state outside of that transaction. Refreshing
attributes usually only makes sense at the start of a transaction
where database rows have not yet been accessed.
:param attribute_names: optional. An iterable collection of
string attribute names indicating a subset of attributes to
be refreshed.
:param with_for_update: optional boolean ``True`` indicating FOR UPDATE
should be used, or may be a dictionary containing flags to
indicate a more specific set of FOR UPDATE flags for the SELECT;
flags should match the parameters of
:meth:`_query.Query.with_for_update`.
Supersedes the :paramref:`.Session.refresh.lockmode` parameter.
.. seealso::
:ref:`session_expire` - introductory material
:meth:`.Session.expire`
:meth:`.Session.expire_all`
:ref:`orm_queryguide_populate_existing` - allows any ORM query
to refresh objects as they would be loaded normally.
""" # noqa: E501
return self._proxied.refresh(
instance,
attribute_names=attribute_names,
with_for_update=with_for_update,
)
def rollback(self) -> None:
r"""Rollback the current transaction in progress.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
If no transaction is in progress, this method is a pass-through.
The method always rolls back
the topmost database transaction, discarding any nested
transactions that may be in progress.
.. seealso::
:ref:`session_rollback`
:ref:`unitofwork_transaction`
""" # noqa: E501
return self._proxied.rollback()
@overload
def scalar(
self,
statement: TypedReturnsRows[Tuple[_T]],
params: Optional[_CoreSingleExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
**kw: Any,
) -> Optional[_T]: ...
@overload
def scalar(
self,
statement: Executable,
params: Optional[_CoreSingleExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
**kw: Any,
) -> Any: ...
def scalar(
self,
statement: Executable,
params: Optional[_CoreSingleExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
**kw: Any,
) -> Any:
r"""Execute a statement and return a scalar result.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Usage and parameters are the same as that of
:meth:`_orm.Session.execute`; the return result is a scalar Python
value.
""" # noqa: E501
return self._proxied.scalar(
statement,
params=params,
execution_options=execution_options,
bind_arguments=bind_arguments,
**kw,
)
@overload
def scalars(
self,
statement: TypedReturnsRows[Tuple[_T]],
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
**kw: Any,
) -> ScalarResult[_T]: ...
@overload
def scalars(
self,
statement: Executable,
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
**kw: Any,
) -> ScalarResult[Any]: ...
def scalars(
self,
statement: Executable,
params: Optional[_CoreAnyExecuteParams] = None,
*,
execution_options: OrmExecuteOptionsParameter = util.EMPTY_DICT,
bind_arguments: Optional[_BindArguments] = None,
**kw: Any,
) -> ScalarResult[Any]:
r"""Execute a statement and return the results as scalars.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
Usage and parameters are the same as that of
:meth:`_orm.Session.execute`; the return result is a
:class:`_result.ScalarResult` filtering object which
will return single elements rather than :class:`_row.Row` objects.
:return: a :class:`_result.ScalarResult` object
.. versionadded:: 1.4.24 Added :meth:`_orm.Session.scalars`
.. versionadded:: 1.4.26 Added :meth:`_orm.scoped_session.scalars`
.. seealso::
:ref:`orm_queryguide_select_orm_entities` - contrasts the behavior
of :meth:`_orm.Session.execute` to :meth:`_orm.Session.scalars`
""" # noqa: E501
return self._proxied.scalars(
statement,
params=params,
execution_options=execution_options,
bind_arguments=bind_arguments,
**kw,
)
@property
def bind(self) -> Optional[Union[Engine, Connection]]:
r"""Proxy for the :attr:`_orm.Session.bind` attribute
on behalf of the :class:`_orm.scoping.scoped_session` class.
""" # noqa: E501
return self._proxied.bind
@bind.setter
def bind(self, attr: Optional[Union[Engine, Connection]]) -> None:
self._proxied.bind = attr
@property
def dirty(self) -> Any:
r"""The set of all persistent instances considered dirty.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class
on behalf of the :class:`_orm.scoping.scoped_session` class.
E.g.::
some_mapped_object in session.dirty
Instances are considered dirty when they were modified but not
deleted.
Note that this 'dirty' calculation is 'optimistic'; most
attribute-setting or collection modification operations will
mark an instance as 'dirty' and place it in this set, even if
there is no net change to the attribute's value. At flush
time, the value of each attribute is compared to its
previously saved value, and if there's no net change, no SQL
operation will occur (this is a more expensive operation so
it's only done at flush time).
To check if an instance has actionable net changes to its
attributes, use the :meth:`.Session.is_modified` method.
""" # noqa: E501
return self._proxied.dirty
@property
def deleted(self) -> Any:
r"""The set of all instances marked as 'deleted' within this ``Session``
.. container:: class_bases
Proxied for the :class:`_orm.Session` class
on behalf of the :class:`_orm.scoping.scoped_session` class.
""" # noqa: E501
return self._proxied.deleted
@property
def new(self) -> Any:
r"""The set of all instances marked as 'new' within this ``Session``.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class
on behalf of the :class:`_orm.scoping.scoped_session` class.
""" # noqa: E501
return self._proxied.new
@property
def identity_map(self) -> IdentityMap:
r"""Proxy for the :attr:`_orm.Session.identity_map` attribute
on behalf of the :class:`_orm.scoping.scoped_session` class.
""" # noqa: E501
return self._proxied.identity_map
@identity_map.setter
def identity_map(self, attr: IdentityMap) -> None:
self._proxied.identity_map = attr
@property
def is_active(self) -> Any:
r"""True if this :class:`.Session` not in "partial rollback" state.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class
on behalf of the :class:`_orm.scoping.scoped_session` class.
.. versionchanged:: 1.4 The :class:`_orm.Session` no longer begins
a new transaction immediately, so this attribute will be False
when the :class:`_orm.Session` is first instantiated.
"partial rollback" state typically indicates that the flush process
of the :class:`_orm.Session` has failed, and that the
:meth:`_orm.Session.rollback` method must be emitted in order to
fully roll back the transaction.
If this :class:`_orm.Session` is not in a transaction at all, the
:class:`_orm.Session` will autobegin when it is first used, so in this
case :attr:`_orm.Session.is_active` will return True.
Otherwise, if this :class:`_orm.Session` is within a transaction,
and that transaction has not been rolled back internally, the
:attr:`_orm.Session.is_active` will also return True.
.. seealso::
:ref:`faq_session_rollback`
:meth:`_orm.Session.in_transaction`
""" # noqa: E501
return self._proxied.is_active
@property
def autoflush(self) -> bool:
r"""Proxy for the :attr:`_orm.Session.autoflush` attribute
on behalf of the :class:`_orm.scoping.scoped_session` class.
""" # noqa: E501
return self._proxied.autoflush
@autoflush.setter
def autoflush(self, attr: bool) -> None:
self._proxied.autoflush = attr
@property
def no_autoflush(self) -> Any:
r"""Return a context manager that disables autoflush.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class
on behalf of the :class:`_orm.scoping.scoped_session` class.
e.g.::
with session.no_autoflush:
some_object = SomeClass()
session.add(some_object)
# won't autoflush
some_object.related_thing = session.query(SomeRelated).first()
Operations that proceed within the ``with:`` block
will not be subject to flushes occurring upon query
access. This is useful when initializing a series
of objects which involve existing database queries,
where the uncompleted object should not yet be flushed.
""" # noqa: E501
return self._proxied.no_autoflush
@property
def info(self) -> Any:
r"""A user-modifiable dictionary.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class
on behalf of the :class:`_orm.scoping.scoped_session` class.
The initial value of this dictionary can be populated using the
``info`` argument to the :class:`.Session` constructor or
:class:`.sessionmaker` constructor or factory methods. The dictionary
here is always local to this :class:`.Session` and can be modified
independently of all other :class:`.Session` objects.
""" # noqa: E501
return self._proxied.info
@classmethod
def close_all(cls) -> None:
r"""Close *all* sessions in memory.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
.. deprecated:: 1.3 The :meth:`.Session.close_all` method is deprecated and will be removed in a future release. Please refer to :func:`.session.close_all_sessions`.
""" # noqa: E501
return Session.close_all()
@classmethod
def object_session(cls, instance: object) -> Optional[Session]:
r"""Return the :class:`.Session` to which an object belongs.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This is an alias of :func:`.object_session`.
""" # noqa: E501
return Session.object_session(instance)
@classmethod
def identity_key(
cls,
class_: Optional[Type[Any]] = None,
ident: Union[Any, Tuple[Any, ...]] = None,
*,
instance: Optional[Any] = None,
row: Optional[Union[Row[Any], RowMapping]] = None,
identity_token: Optional[Any] = None,
) -> _IdentityKeyType[Any]:
r"""Return an identity key.
.. container:: class_bases
Proxied for the :class:`_orm.Session` class on
behalf of the :class:`_orm.scoping.scoped_session` class.
This is an alias of :func:`.util.identity_key`.
""" # noqa: E501
return Session.identity_key(
class_=class_,
ident=ident,
instance=instance,
row=row,
identity_token=identity_token,
)
# END PROXY METHODS scoped_session
ScopedSession = scoped_session
"""Old name for backwards compatibility."""