相关疑难解决方法(0)

我有SQLAlchemy声明的以下模型类:

class User(Base):
    id = Column(Integer, primary_key=True)
    name = Column(String, nullable=False, unique=True)
    created_at = Colmn(DateTime, nullable=False, default=func.now())

class Post(Base):
    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey(User.id), nullable=False)
    user = relationship(User, backref=backref('posts', lazy='dynamic'))
    title = Column(String, nullable=False)
    body = Column(Text, nullable=False)
    created_at = Colmn(DateTime, nullable=False, default=func.now())

正如我所引用的,这些模型有一个关系,其backref命名为postsset-enabled(通过lazy='dynamic'选项).因为一些用户可能拥有大量帖子而大多数用户没有.

有了这些模型,我试过joinedload了User.posts,但我遇到的错误:

>>> users = session.query(User).options(joinedload(User.posts))[:30]
Traceback (most recent call last):
  ...
InvalidRequestError: 'User.posts' does not support object population - eager loading cannot be applied.

有办法解决这种情况吗？我需要遵循以下两个功能: …