SQLAlchemy：如何将关系定义为其他两个关系的联合？

我如何实现一个自引用的多对多关系，它实际上是两个其他关系的联合

该关系应返回用户与网络中其他用户之间存在的所有FaceBookFriendly模型。用户可能有指向另一个现有用户的FaceBookFriendly，但由于FB API中断、隐私控制等原因，现有用户对该用户的镜像FBFriendly可能不存在

# This class is necessary for python-social-auth
# A UserSocialAuth model only exists for users who are in the network
class UserSocialAuth(_AppSession, Base, SQLAlchemyUserMixin):
    """Social Auth association model"""
    __tablename__ = 'social_auth_usersocialauth'
    __table_args__ = (UniqueConstraint('provider', 'uid'),)
    id = Column(Integer, primary_key=True)
    provider = Column(String(32))
    uid = Column(String(UID_LENGTH))
    extra_data = Column(JSONType())
    user_id = Column(
        Integer, ForeignKey(User.id), nullable=False, index=True)
    user = relationship(
        User,
        backref=backref('social_auth', lazy='dynamic')
    )

    other_facebook_friendships = relationship(
        FacebookFriendship,
        primaryjoin=and_(
            uid == FacebookFriendship.fb_uid_friend,
            provider == 'facebook'
        ),
        foreign_keys=[provider, uid],
        viewonly=True,
        uselist=True,
        lazy='dynamic',
    )

此关系查找从此用户指向任何现有用户的FaceBookFriendly模型

    facebook_friendships = relationship(
        FacebookFriendship,
        primaryjoin=and_(
            user_id == FacebookFriendship.user_id,
            provider == 'facebook'
        ),
        secondary=FacebookFriendship.__table__,
        secondaryjoin=uid == FacebookFriendship.fb_uid_friend,
        foreign_keys=[provider, user_id, uid],
        viewonly=True,
        uselist=True,
        lazy='dynamic',
    )

此关系查找指向此用户的FaceBookFriendly模型

# This class is necessary for python-social-auth
# A UserSocialAuth model only exists for users who are in the network
class UserSocialAuth(_AppSession, Base, SQLAlchemyUserMixin):
    """Social Auth association model"""
    __tablename__ = 'social_auth_usersocialauth'
    __table_args__ = (UniqueConstraint('provider', 'uid'),)
    id = Column(Integer, primary_key=True)
    provider = Column(String(32))
    uid = Column(String(UID_LENGTH))
    extra_data = Column(JSONType())
    user_id = Column(
        Integer, ForeignKey(User.id), nullable=False, index=True)
    user = relationship(
        User,
        backref=backref('social_auth', lazy='dynamic')
    )

    other_facebook_friendships = relationship(
        FacebookFriendship,
        primaryjoin=and_(
            uid == FacebookFriendship.fb_uid_friend,
            provider == 'facebook'
        ),
        foreign_keys=[provider, uid],
        viewonly=True,
        uselist=True,
        lazy='dynamic',
    )

我能够使用hybrid_属性装饰器来表示联合查询，但这阻止了像any（）一样使用比较器或使用关联代理，至少从我所知道的

    # Can I rewrite this using relationship()?
    @hybrid_property
    def all_facebook_friendships(self):
        return self.facebook_friendships.union(
            self.other_facebook_friendships).correlate(
            FacebookFriendship)

# FBFriendship models are created for every friend that a user has,
# regardless of whether they're in the network or not.
class FacebookFriendship(Base):
    __tablename__ = u'user_fb_friend'

    user_id = Column(Integer, sa.ForeignKey(User.id), primary_key=True)

    user = relationship(
        User, backref=backref('facebook_friendships', lazy='dynamic'),
        primaryjoin=User.id == user_id)

    fb_uid_friend = Column(sa.String(length=255), primary_key=True)

最后，我想像查询任何其他InstrumentedAttribute一样查询此关系：

UserSocialAuth.query.filter（UserSocialAuth.all\u facebook\u friendships.any（））.all（）

并在用户模型上定义关联\u代理：

User.all\u facebook\u friends=association\u proxy（'all\u facebook\u friends'，'User'）

对不起，这个问题太长了，但是我已经试了几天了，都没有用了

相关的：

---

使用上面链接的zzzeek解决方案，我创建了一个自引用M2M关系，使用select语句作为relationship（）的“次要”参数

---

我相信，如果您使用zzzeek的解决方案（使用链接到的

UNION

s），您应该能够完成所有需要的操作，使用

any

进行查询也可以。