events.py 文件源码

def before_compile(self, query):
        """Receive the :class:`.Query` object before it is composed into a
        core :class:`.Select` object.

        This event is intended to allow changes to the query given::

            @event.listens_for(Query, "before_compile", retval=True)
            def no_deleted(query):
                for desc in query.column_descriptions:
                    if desc['type'] is User:
                        entity = desc['entity']
                        query = query.filter(entity.deleted == False)
                return query

        The event should normally be listened with the ``retval=True``
        parameter set, so that the modified query may be returned.


        """