Cleanup listing relations

def cleanup_relations(self):
        """Cleanup listing relations"""
        collections = self.collections
        for relation in [x for col in collections.values()
                         for x in col.model.relations.values()]:
            db.session.query(relation)\
                       .filter(~relation.listing.any())\
                       .delete(synchronize_session=False)
        db.session.commit()