def sort_query(self, query, sort_info):
        for sort_opt in sort_info:
            field = sort_opt['field']
            if not hasattr(self.model, field):
                raise InvalidSort("{} has no attribute {}".format(self.model.__name__, field))
            query = query.order_by(getattr(getattr(self.model, field), sort_opt['order'])())
        return query