Python SQLAlchemy基本操作和常用技巧(包含大量实例,非常好)

2019-10-06 16:15:37丽君

                query = session.query(columns)
                if isinstance(columns, str):
                    query = query.select_from(cls)
        else:
            query = session.query(cls)
        if order_by is not None:
            if isinstance(order_by, (tuple, list)):
                query = query.order_by(*order_by)
            else:
                query = query.order_by(order_by)
        if offset:
            query = query.offset(offset)
        if limit:
            query = query.limit(limit)
        if lock_mode:
            query = query.with_lockmode(lock_mode)
        return query.all()
    BaseModel.get_all = get_all

    @classmethod
    def count_all(cls, session, lock_mode=None):
        query = session.query(func.count('*')).select_from(cls)
        if lock_mode:
            query = query.with_lockmode(lock_mode)
        return query.scalar()
    BaseModel.count_all = count_all

    @classmethod
    def exist(cls, session, id, lock_mode=None):
        if hasattr(cls, 'id'):
            query = session.query(func.count('*')).select_from(cls).filter(cls.id == id)
            if lock_mode:
                query = query.with_lockmode(lock_mode)
            return query.scalar() > 0
        return False
    BaseModel.exist = exist

    @classmethod
    def set_attr(cls, session, id, attr, value):
        if hasattr(cls, 'id'):
            session.query(cls).filter(cls.id == id).update({