sqlalchemy.orm.util

Return True if the given object has a database identity. This typically corresponds to the object being in either the persistent or detached state. .. seealso:: :func:`.was_deleted`

Generate "identity key" tuples, as are used as keys in the :attr:`.Session.identity_map` dictionary. This function has several call styles: * ``identity_key(class, ident, identity_token=token)`` This form receives a mapped class and a primary key scalar or tuple as an argument. E.g.:: >>> identity_key(MyClass, (1, 2)) (<class '__main__.MyClass'>, (1, 2), None) :param class: mapped class (must be a positional argument) :param ident: primary key, may be a scalar or tuple argument. :param identity_token: optional identity token .. versionadded:: 1.2 added identity_token * ``identity_key(instance=instance)`` This form will produce the identity key for a given instance. The instance need not be persistent, only that its primary key attributes are populated (else the key will contain ``None`` for those missing values). E.g.:: >>> instance = MyClass(1, 2) >>> identity_key(instance=instance) (<class '__main__.MyClass'>, (1, 2), None) In this form, the given instance is ultimately run though :meth:`_orm.Mapper.identity_key_from_instance`, which will have the effect of performing a database check for the corresponding row if the object is expired. :param instance: object instance (must be given as a keyword arg) * ``identity_key(class, row=row, identity_token=token)`` This form is similar to the class/tuple form, except is passed a database result row as a :class:`.Row` or :class:`.RowMapping` object. E.g.:: >>> row = engine.execute(\ text("select * from table where a=1 and b=2")\ ).first() >>> identity_key(MyClass, row=row) (<class '__main__.MyClass'>, (1, 2), None) :param class: mapped class (must be a positional argument) :param row: :class:`.Row` row returned by a :class:`_engine.CursorResult` (must be given as a keyword arg) :param identity_token: optional identity token .. versionadded:: 1.2 added identity_token

Create a ``UNION`` statement used by a polymorphic mapper. See :ref:`concrete_inheritance` for an example of how this is used. :param table_map: mapping of polymorphic identities to :class:`_schema.Table` objects. :param typecolname: string name of a "discriminator" column, which will be derived from the query, producing the polymorphic identity for each row. If ``None``, no polymorphic discriminator is generated. :param aliasname: name of the :func:`~sqlalchemy.sql.expression.alias()` construct generated. :param cast_nulls: if True, non-existent columns, which are represented as labeled NULLs, will be passed into CAST. This is a legacy behavior that is problematic on some backends such as Oracle - in which case it can be set to False.

Return True if the given object was deleted within a session flush. This is regardless of whether or not the object is persistent or detached. .. seealso:: :attr:`.InstanceState.was_deleted`

Create filtering criterion that relates this query's primary entity to the given related instance, using established :func:`_orm.relationship()` configuration. E.g.:: stmt = select(Address).where(with_parent(some_user, User.addresses)) The SQL rendered is the same as that rendered when a lazy loader would fire off from the given parent on that attribute, meaning that the appropriate state is taken from the parent object in Python without the need to render joins to the parent table in the rendered statement. The given property may also make use of :meth:`_orm.PropComparator.of_type` to indicate the left side of the criteria:: a1 = aliased(Address) a2 = aliased(Address) stmt = select(a1, a2).where( with_parent(u1, User.addresses.of_type(a2)) ) The above use is equivalent to using the :func:`_orm.with_parent.from_entity` argument:: a1 = aliased(Address) a2 = aliased(Address) stmt = select(a1, a2).where( with_parent(u1, User.addresses, from_entity=a2) ) :param instance: An instance which has some :func:`_orm.relationship`. :param property: Class-bound attribute, which indicates what relationship from the instance should be used to reconcile the parent/child relationship. :param from_entity: Entity in which to consider as the left side. This defaults to the "zero" entity of the :class:`_query.Query` itself. .. versionadded:: 1.2