Classe « SessionEvents »

Méthode sqlalchemy.orm.SessionEvents.persistent_to_deleted

Signature de la méthode persistent_to_deleted

def persistent_to_deleted(self, session, instance) 

Description

persistent_to_deleted.__doc__

Intercept the "persistent to deleted" transition for a specific object.

.. container:: event_signatures

     Example argument forms::

        from sqlalchemy import event


        @event.listens_for(SomeSessionOrFactory, 'persistent_to_deleted')
        def receive_persistent_to_deleted(session, instance):
            "listen for the 'persistent_to_deleted' event"

            # ... (event handling logic) ...


This event is invoked when a persistent object's identity
is deleted from the database within a flush, however the object
still remains associated with the :class:`.Session` until the
transaction completes.

If the transaction is rolled back, the object moves again
to the persistent state, and the
:meth:`.SessionEvents.deleted_to_persistent` event is called.
If the transaction is committed, the object becomes detached,
which will emit the :meth:`.SessionEvents.deleted_to_detached`
event.

Note that while the :meth:`.Session.delete` method is the primary
public interface to mark an object as deleted, many objects
get deleted due to cascade rules, which are not always determined
until flush time.  Therefore, there's no way to catch
every object that will be deleted until the flush has proceeded.
the :meth:`.SessionEvents.persistent_to_deleted` event is therefore
invoked at the end of a flush.

.. versionadded:: 1.1

.. seealso::

    :ref:`session_lifecycle_events`