python - SqlAlchemy 没有定义这样的多态身份

Question

我正在尝试存储第3方站点的用户oauth详细信息，BaseConnection表用于存储连接的基本信息

class BaseConnection(Base):
    __tablename__ = "BaseConnection"
    id = Column(Integer, primary_key=True)
    username = Column(Unicode(255),
                      ForeignKey('users.username'))
    type = Column(Unicode(255))
    is_active = Column(Boolean, default=False)
    last_connection = Column(DateTime, onupdate=datetime.utcnow)

    __mapper_args__ = {
        'polymorphic_identity': 'BaseConnection',
        'polymorphic_on': type
    }

    def __init__(self, username, type, is_active):
        self.username = username
        self.type = type
        self.is_active = is_active

Twitter 连接用于存储 Twitter 帐户的 ouath 详细信息

class TwitterConnection(Base):
    __tablename__ = "TwitterConnection"

    connection_id = Column(Integer, ForeignKey('BaseConnection.id'),
                           primary_key=True)
    uid = Column(Unicode(255))
    access_key = Column(Unicode(255))
    access_secret = Column(Unicode(255))
    twitter_username = Column(Unicode(255))
    refresh_date = Column(DateTime)

    __mapper_args__ = {
        'polymorphic_identity': 'TwitterConnection'
    }

    def __init__(self, connection_id, 
                 uid, access_key, access_secret, twitter_username):
        self.connection_id = connection_id
        self.uid = uid
        self.access_key = access_key
        self.access_secret = access_secret
        self.twitter_username = twitter_username
        self.refresh_date = datetime.now()

然后我使用代码将第一个详细信息添加到表格

base_connection = BaseConnection('admin', TwitterConnection.__name__, True)
base_connection.last_connection = datetime.now()
DBSession.add(base_connection)
DBSession.flush()
tconnection = TwitterConnection(
                 base_connection.id,
                 uid=u'1234',
                 access_key=u'dummy',
                 access_secret=u'dummy',
                 twitter_username='dummy')
DBSession.add(tconnection)
DBSession.flush()
transaction.commit()

我正在尝试编写一个查询来查找具有特定用户名的用户的所有第三方帐户

qry = BaseConnection.query.filter(
                BaseConnection.username==username)
qry.all()

上面的查询给出了错误

`AssertionError: No such polymorphic_identity u'TwitterConnection' is defined

我是 sqlalchemy 的新手，感谢帮助，谢谢。

Answer 1

抱歉，

class TwitterConnection(Base):

应该是

class TwitterConnection(BaseConnection):