def by_group_name(cls, group_name, db_session=None):
        """
        fetch group by name

        :param group_name:
        :param db_session:
        :return:
        """
        db_session = get_db_session(db_session)
        query = db_session.query(cls.model).filter(cls.model.group_name == group_name)
        return query.first()
def by_group_name ( cls , group_name , db_session = None ) : db_session = get_db_session ( db_session ) query = db_session . query ( cls . model ) . filter ( cls . model . group_name == group_name ) return query . first ( )
fetch group by name

        :param group_name:
        :param db_session:
        :return: