SQLalchemy - ＆＃39; AppenderQuery＆＃39;对象没有属性＆＃39;序列化＆＃39;

Question

所以，我在我的一个类中创建了一个JSON返回属性，但是在尝试使用其中一个属性时出现错误：

class Posts(Base):
    __tablename__ = 'posts'

    post_id = Column(Integer, nullable = False, primary_key = True)
    text = Column(String, nullable = False)
    date = Column(DateTime(timezone=True), server_default=func.now())
    deleted = Column(Integer, default = 0)
    owner = Column(Integer, ForeignKey('users.id'))
    owner_rel = relationship('Users')
    comments_rel = relationship('Comments', cascade='all, delete-orphan', lazy='dynamic')

    @property
    def serialize(self):
        # Returns Data Object In Proper Format
        return {
            'postID': self.post_id,
            'text': self.text,
            'date': self.date,
            'owner': self.owner,
            'postOwner': self.owner_rel.serialize,
            'comments': self.comments_rel.serialize
        }



class Comments(Base):
    __tablename__ = 'comments'

    comment_id = Column(Integer, nullable = False, primary_key = True)
    post_id = Column(Integer, ForeignKey('posts.post_id'))
    post_rel = relationship('Posts')
    text = Column(String, nullable = False)
    date = Column(DateTime(timezone=True), server_default=func.now())
    deleted = Column(Integer, default = 0)
    owner = Column(Integer, ForeignKey('users.id'))
    owner_rel = relationship('Users')

    @property
    def serialize(self):
        # Returns Data Object In Proper Format
        return {
            'commentID': self.comment_id,
            'postID': self.post_id,
            'text': self.text,
            'date': self.date,
            'ownerID': self.owner,
            'owner': self.owner_rel.serialize
        }

我得到了这个错误 - ＆＃39; AppenderQuery＆＃39;对象没有属性＆＃39;序列化＆＃39;

帮助？