Set the constraints for an eager load of the relation.

        :type models: list

def add_eager_constraints(self, models):
        """
        Set the constraints for an eager load of the relation.

        :type models: list
        """
        table = self._parent.get_table()

        self._query.where_in("%s.%s" % (table, self._first_key), self.get_keys(models))