Module « sqlalchemy.orm »

Fonction contains_eager - module sqlalchemy.orm

Signature de la fonction contains_eager

def contains_eager(*keys, **kw) 

Description

contains_eager.__doc__

Indicate that the given attribute should be eagerly loaded from
    columns stated manually in the query.

    This function is part of the :class:`_orm.Load` interface and supports
    both method-chained and standalone operation.

    The option is used in conjunction with an explicit join that loads
    the desired rows, i.e.::

        sess.query(Order).\
                join(Order.user).\
                options(contains_eager(Order.user))

    The above query would join from the ``Order`` entity to its related
    ``User`` entity, and the returned ``Order`` objects would have the
    ``Order.user`` attribute pre-populated.

    It may also be used for customizing the entries in an eagerly loaded
    collection; queries will normally want to use the
    :meth:`_query.Query.populate_existing` method assuming the primary
    collection of parent objects may already have been loaded::

        sess.query(User).\
            join(User.addresses).\
            filter(Address.email_address.like('%@aol.com')).\
            options(contains_eager(User.addresses)).\
            populate_existing()

    See the section :ref:`contains_eager` for complete usage details.

    .. seealso::

        :ref:`loading_toplevel`

        :ref:`contains_eager`