python - 属性错误 : 'InstrumentedList' object has no attribute

Question

我有这些表格:

class Thing(Base):
    __tablename__ = 'thing'
    id = Column(Integer, primary_key=True)

class User(Base):
    __tablename__ = 'user'
    id = Column(Integer, primary_key=True)

class Voteinfo(Base):
    __tablename__ = 'voteinfo'
    thing_id = Column(Integer, ForeignKey('thing.id'), primary_key=True)
    thing = relationship('Thing', backref='voteinfo')
    upvotes = Column(Integer)
    downvotes = Column(Integer)

    def __init__(self, thing)
        self.thing = thing

class VoteThing(Base):
    __tablename__ = 'votething'
    id = Column(Integer, primary_key=True)
    voter_id = Column(Integer, ForeignKey('voter.id'))
    voter = relationship('Voter', backref='votescast')
    thing_id = Column(Integer, ForeignKey('thing.id'))
    thing = relationship('Thing', backref='votesreceived')
    value = Column(Boolean)

    def __init__(self, voter, thing, value):
        if value is True:
            thing.voteinfo.upvotes += 1
        else:
            thing.voteinfo.downvotes += 1

当我尝试运行它时，我在“if value is True”子句中得到了这个错误代码:

AttributeError: 'InstrumentedList' object has no attribute 'upvotes'

我试过为 Voteinfo 提供自己的唯一 ID 并向关系中添加 uselist=False。我试过将与事物的关系从 VoteThing 替换为 Voteinfo，但这也无济于事。我不知道 InstrumentedList 是什么。这是怎么回事？

Answer 1

如文档中所述，此处:https://docs.sqlalchemy.org/en/latest/orm/basic_relationships.html#one-to-one ，您必须将 uselist=False 添加到反向引用而不是关系中。

thing = relationship('Thing', backref=backref('voteinfo', uselist=False))