events.py 文件源码

def before_flush(self, session, flush_context, instances):
        """Execute before flush process has started.

        :param session: The target :class:`.Session`.
        :param flush_context: Internal :class:`.UOWTransaction` object
         which handles the details of the flush.
        :param instances: Usually ``None``, this is the collection of
         objects which can be passed to the :meth:`.Session.flush` method
         (note this usage is deprecated).

        .. seealso::

            :meth:`~.SessionEvents.after_flush`

            :meth:`~.SessionEvents.after_flush_postexec`

            :ref:`session_persistence_events`

        """