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Module « sqlalchemy.orm »

Fonction join - module sqlalchemy.orm

Signature de la fonction join

def join(left: '_FromClauseArgument', right: '_FromClauseArgument', onclause: 'Optional[_OnClauseArgument]' = None, isouter: 'bool' = False, full: 'bool' = False) -> '_ORMJoin' 

Description

help(sqlalchemy.orm.join)

Produce an inner join between left and right clauses.

:func:`_orm.join` is an extension to the core join interface
provided by :func:`_expression.join()`, where the
left and right selectable may be not only core selectable
objects such as :class:`_schema.Table`, but also mapped classes or
:class:`.AliasedClass` instances.   The "on" clause can
be a SQL expression or an ORM mapped attribute
referencing a configured :func:`_orm.relationship`.

:func:`_orm.join` is not commonly needed in modern usage,
as its functionality is encapsulated within that of the
:meth:`_sql.Select.join` and :meth:`_query.Query.join`
methods. which feature a
significant amount of automation beyond :func:`_orm.join`
by itself.  Explicit use of :func:`_orm.join`
with ORM-enabled SELECT statements involves use of the
:meth:`_sql.Select.select_from` method, as in::

    from sqlalchemy.orm import join

    stmt = (
        select(User)
        .select_from(join(User, Address, User.addresses))
        .filter(Address.email_address == "foo@bar.com")
    )

In modern SQLAlchemy the above join can be written more
succinctly as::

    stmt = (
        select(User)
        .join(User.addresses)
        .filter(Address.email_address == "foo@bar.com")
    )

.. warning:: using :func:`_orm.join` directly may not work properly
   with modern ORM options such as :func:`_orm.with_loader_criteria`.
   It is strongly recommended to use the idiomatic join patterns
   provided by methods such as :meth:`.Select.join` and
   :meth:`.Select.join_from` when creating ORM joins.

.. seealso::

    :ref:`orm_queryguide_joins` - in the :ref:`queryguide_toplevel` for
    background on idiomatic ORM join patterns

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