Module « sqlalchemy.orm »

Classe « sessionmaker »

Informations générales

Héritage

builtins.object
    _SessionClassMethods
        sessionmaker

Définition

class sessionmaker(_SessionClassMethods):

Description _{[extrait de sessionmaker.__doc__]}

A configurable :class:`.Session` factory.

    The :class:`.sessionmaker` factory generates new
    :class:`.Session` objects when called, creating them given
    the configurational arguments established here.

    e.g.::

        from sqlalchemy import create_engine
        from sqlalchemy.orm import sessionmaker

        # an Engine, which the Session will use for connection
        # resources
        engine = create_engine('postgresql://scott:tiger@localhost/')

        Session = sessionmaker(engine)

        with Session() as session:
            session.add(some_object)
            session.add(some_other_object)
            session.commit()

    Context manager use is optional; otherwise, the returned
    :class:`_orm.Session` object may be closed explicitly via the
    :meth:`_orm.Session.close` method.   Using a
    ``try:/finally:`` block is optional, however will ensure that the close
    takes place even if there are database errors::

        session = Session()
        try:
            session.add(some_object)
            session.add(some_other_object)
            session.commit()
        finally:
            session.close()

    :class:`.sessionmaker` acts as a factory for :class:`_orm.Session`
    objects in the same way as an :class:`_engine.Engine` acts as a factory
    for :class:`_engine.Connection` objects.  In this way it also includes
    a :meth:`_orm.sessionmaker.begin` method, that provides a context
    manager which both begins and commits a transaction, as well as closes
    out the :class:`_orm.Session` when complete, rolling back the transaction
    if any errors occur::

        Session = sessionmaker(engine)

        with Session.begin() as session:
            session.add(some_object)
            session.add(some_other_object)
        # commits transaction, closes session

    .. versionadded:: 1.4

    When calling upon :class:`_orm.sessionmaker` to construct a
    :class:`_orm.Session`, keyword arguments may also be passed to the
    method; these arguments will override that of the globally configured
    parameters.  Below we use a :class:`_orm.sessionmaker` bound to a certain
    :class:`_engine.Engine` to produce a :class:`_orm.Session` that is instead
    bound to a specific :class:`_engine.Connection` procured from that engine::

        Session = sessionmaker(engine)

        # bind an individual session to a connection

        with engine.connect() as connection:
            with Session(bind=connection) as session:
                # work with session

    The class also includes a method :meth:`_orm.sessionmaker.configure`, which
    can be used to specify additional keyword arguments to the factory, which
    will take effect for subsequent :class:`.Session` objects generated. This
    is usually used to associate one or more :class:`_engine.Engine` objects
    with an existing
    :class:`.sessionmaker` factory before it is first used::

        # application starts, sessionmaker does not have
        # an engine bound yet
        Session = sessionmaker()

        # ... later, when an engine URL is read from a configuration
        # file or other events allow the engine to be created
        engine = create_engine('sqlite:///foo.db')
        Session.configure(bind=engine)

        sess = Session()
        # work with session

    .. seealso::

        :ref:`session_getting` - introductory text on creating
        sessions using :class:`.sessionmaker`.

    

Constructeur(s)

Signature du constructeur	Description
__init__(self, bind=None, class_=<class 'sqlalchemy.orm.session.Session'>, autoflush=True, autocommit=False, expire_on_commit=True, info=None, **kw)	Construct a new :class:`.sessionmaker`. [extrait de __init__.__doc__]

Liste des opérateurs

Opérateurs hérités de la classe object

__eq__, __ge__, __gt__, __le__, __lt__, __ne__

Méthodes héritées de la classe _SessionClassMethods

__init_subclass__, __subclasshook__, close_all, identity_key, object_session

Méthodes héritées de la classe object

__delattr__, __dir__, __format__, __getattribute__, __hash__, __reduce__, __reduce_ex__, __setattr__, __sizeof__, __str__