diff options
Diffstat (limited to 'lib/sqlalchemy/orm')
| -rw-r--r-- | lib/sqlalchemy/orm/scoping.py | 1577 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/session.py | 6 |
2 files changed, 1579 insertions, 4 deletions
diff --git a/lib/sqlalchemy/orm/scoping.py b/lib/sqlalchemy/orm/scoping.py index 9eb80a107..cc9d5a23b 100644 --- a/lib/sqlalchemy/orm/scoping.py +++ b/lib/sqlalchemy/orm/scoping.py @@ -11,6 +11,7 @@ from . import exc as orm_exc from .base import class_mapper 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 @@ -225,6 +226,1582 @@ class scoped_session(ScopedSessionMixin): 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): + 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): + 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: Any, _warn: bool = True) -> None: + r"""Place an object in the ``Session``. + + .. container:: class_bases + + Proxied for the :class:`_orm.Session` class on + behalf of the :class:`_orm.scoping.scoped_session` class. + + Its state will be persisted to the database on the next flush + operation. + + Repeated calls to ``add()`` will be ignored. The opposite of ``add()`` + is ``expunge()``. + + + """ # noqa: E501 + + return self._proxied.add(instance, _warn=_warn) + + def add_all(self, instances): + r"""Add the given collection of instances to 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.add_all(instances) + + def begin(self, nested=False, _subtrans=False): + 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, _subtrans=_subtrans) + + def begin_nested(self): + 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. + + + """ # noqa: E501 + + return self._proxied.begin_nested() + + def close(self): + 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:: + + 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. + + .. 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` + + + """ # noqa: E501 + + return self._proxied.close() + + 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. + + If no transaction is in progress, the method will first + "autobegin" a new transaction and commit. + + The outermost database transaction is committed unconditionally, + automatically releasing any SAVEPOINTs in effect. + + .. seealso:: + + :ref:`session_committing` + + :ref:`unitofwork_transaction` + + + """ # noqa: E501 + + return self._proxied.commit() + + def connection( + self, + bind_arguments: Optional[Dict[str, Any]] = None, + execution_options: Optional["_ExecuteOptions"] = 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): + 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 database delete operation occurs upon ``flush()``. + + + """ # noqa: E501 + + return self._proxied.delete(instance) + + def execute( + self, + statement: "Executable", + params: Optional["_ExecuteParams"] = None, + execution_options: "_ExecuteOptions" = util.EMPTY_DICT, + bind_arguments: Optional[Dict[str, Any]] = None, + _parent_execute_state: Optional[Any] = None, + _add_event: Optional[Any] = None, + ): + 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, attribute_names=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): + 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): + 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): + 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=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, + ident, + options=None, + populate_existing=False, + with_for_update=None, + identity_token=None, + execution_options=None, + ): + 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 + + :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, + ) + + def get_bind( + self, + mapper=None, + clause=None, + bind=None, + _sa_skip_events=None, + _sa_skip_for_implicit_returning=False, + ): + 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, + ) + + def is_modified(self, instance, include_collections=True): + 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 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, + return_defaults=False, + update_changed_only=True, + preserve_order=True, + ): + 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. + + The bulk save feature allows mapped objects to be used as the + source of simple INSERT and UPDATE operations which can be more easily + grouped together into higher performing "executemany" + operations; the extraction of data from the objects is also performed + using a lower-latency process that ignores whether or not attributes + have actually been modified in the case of UPDATEs, and also ignores + SQL expressions. + + The objects as given are not added to the session and no additional + state is established on them. If the + :paramref:`_orm.Session.bulk_save_objects.return_defaults` flag is set, + then server-generated primary key values will be assigned to the + returned objects, but **not server side defaults**; this is a + limitation in the implementation. If stateful objects are desired, + please use the standard :meth:`_orm.Session.add_all` approach or + as an alternative newer mass-insert features such as + :ref:`orm_dml_returning_objects`. + + .. warning:: + + The bulk save feature allows for a lower-latency INSERT/UPDATE + of rows at the expense of most other unit-of-work features. + Features such as object management, relationship handling, + and SQL clause support are **silently omitted** in favor of raw + INSERT/UPDATES of records. + + Please note that newer versions of SQLAlchemy are **greatly + improving the efficiency** of the standard flush process. It is + **strongly recommended** to not use the bulk methods as they + represent a forking of SQLAlchemy's functionality and are slowly + being moved into legacy status. New features such as + :ref:`orm_dml_returning_objects` are both more efficient than + the "bulk" methods and provide more predictable functionality. + + **Please read the list of caveats at** + :ref:`bulk_operations_caveats` **before using this method, and + fully test and confirm the functionality of all code developed + using these systems.** + + :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. + + .. versionadded:: 1.3 + + .. seealso:: + + :ref:`bulk_operations` + + :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, mappings, return_defaults=False, render_nulls=False + ): + 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. + + The bulk insert feature allows plain Python dictionaries to be used as + the source of simple INSERT operations which can be more easily + grouped together into higher performing "executemany" + operations. Using dictionaries, there is no "history" or session + state management features in use, reducing latency when inserting + large numbers of simple rows. + + The values within the dictionaries as given are typically passed + without modification into Core :meth:`_expression.Insert` constructs, + after + organizing the values within them across the tables to which + the given mapper is mapped. + + .. versionadded:: 1.0.0 + + .. warning:: + + The bulk insert feature allows for a lower-latency INSERT + of rows at the expense of most other unit-of-work features. + Features such as object management, relationship handling, + and SQL clause support are **silently omitted** in favor of raw + INSERT of records. + + Please note that newer versions of SQLAlchemy are **greatly + improving the efficiency** of the standard flush process. It is + **strongly recommended** to not use the bulk methods as they + represent a forking of SQLAlchemy's functionality and are slowly + being moved into legacy status. New features such as + :ref:`orm_dml_returning_objects` are both more efficient than + the "bulk" methods and provide more predictable functionality. + + **Please read the list of caveats at** + :ref:`bulk_operations_caveats` **before using this method, and + fully test and confirm the functionality of all code developed + using these systems.** + + :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, 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_insert_mappings.return_defaults` + **greatly reduces the performance gains** of the method overall. + If the rows + to be inserted only refer to a single table, then there is no + reason this flag should be set as the returned default information + is not used. + + :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. + + .. versionadded:: 1.1 + + .. seealso:: + + :ref:`bulk_operations` + + :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, mappings): + 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. + + The bulk update feature allows plain Python dictionaries to be used as + the source of simple UPDATE operations which can be more easily + grouped together into higher performing "executemany" + operations. Using dictionaries, there is no "history" or session + state management features in use, reducing latency when updating + large numbers of simple rows. + + .. versionadded:: 1.0.0 + + .. warning:: + + The bulk update feature allows for a lower-latency UPDATE + of rows at the expense of most other unit-of-work features. + Features such as object management, relationship handling, + and SQL clause support are **silently omitted** in favor of raw + UPDATES of records. + + Please note that newer versions of SQLAlchemy are **greatly + improving the efficiency** of the standard flush process. It is + **strongly recommended** to not use the bulk methods as they + represent a forking of SQLAlchemy's functionality and are slowly + being moved into legacy status. New features such as + :ref:`orm_dml_returning_objects` are both more efficient than + the "bulk" methods and provide more predictable functionality. + + **Please read the list of caveats at** + :ref:`bulk_operations_caveats` **before using this method, and + fully test and confirm the functionality of all code developed + using these systems.** + + :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:: + + :ref:`bulk_operations` + + :meth:`.Session.bulk_insert_mappings` + + :meth:`.Session.bulk_save_objects` + + + """ # noqa: E501 + + return self._proxied.bulk_update_mappings(mapper, mappings) + + def merge(self, instance, load=True, options=None): + 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. + + .. versionchanged:: 1.1 - :meth:`.Session.merge` will now reconcile + pending objects with overlapping primary keys in the same way + as persistent. See :ref:`change_3601` for discussion. + + :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) + + def query(self, *entities: _ColumnsClauseArgument, **kwargs: Any) -> Query: + 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, attribute_names=None, with_for_update=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. + Unloaded relationship attributes will remain unloaded, as will + relationship attributes that were originally lazy loaded. + + .. versionadded:: 1.4 - the :meth:`_orm.Session.refresh` method + can also refresh eagerly loaded attributes. + + .. 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): + 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() + + def scalar( + self, + statement, + params=None, + execution_options=util.EMPTY_DICT, + bind_arguments=None, + **kw, + ): + 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, + ) + + def scalars( + self, + statement, + params=None, + execution_options=util.EMPTY_DICT, + bind_arguments=None, + **kw, + ): + 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 + + + """ # 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) -> identity.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: identity.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 + + @property + def autocommit(self) -> Any: + r"""Proxy for the :attr:`_orm.Session.autocommit` attribute + on behalf of the :class:`_orm.scoping.scoped_session` class. + + """ # noqa: E501 + + return self._proxied.autocommit + + @autocommit.setter + def autocommit(self, attr: Any) -> None: + self._proxied.autocommit = attr + + @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: Any) -> "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_=None, + ident=None, + *, + instance=None, + row=None, + identity_token=None, + ) -> _IdentityKeyType: + 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.""" diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py index 6279c17fb..77a97936b 100644 --- a/lib/sqlalchemy/orm/session.py +++ b/lib/sqlalchemy/orm/session.py @@ -56,7 +56,6 @@ from ..sql import coercions from ..sql import dml from ..sql import roles from ..sql import visitors -from ..sql._typing import _ColumnsClauseArgument from ..sql.base import CompileState from ..sql.selectable import LABEL_STYLE_TABLENAME_PLUS_COL from ..util.typing import Literal @@ -64,6 +63,7 @@ from ..util.typing import Literal if typing.TYPE_CHECKING: from .mapper import Mapper from ..engine import Row + from ..sql._typing import _ColumnsClauseArgument from ..sql._typing import _ExecuteOptions from ..sql._typing import _ExecuteParams from ..sql.base import Executable @@ -2043,9 +2043,7 @@ class Session(_SessionClassMethods): % (", ".join(context),), ) - def query( - self, *entities: "_ColumnsClauseArgument", **kwargs: Any - ) -> "Query": + def query(self, *entities: _ColumnsClauseArgument, **kwargs: Any) -> Query: """Return a new :class:`_query.Query` object corresponding to this :class:`_orm.Session`. |