flask-sqlalchemy，一对多关系，外键变为NULL

debugcn 发表于 Dev

赵敏珠

我有用户表和专辑表等。和用户专辑有一对多的关系。

但是当用户关联一张或多张专辑时，专辑表中不包括最新专辑的外键变为null。这是 user_uid=1 有 3 个专辑和 user_uid=2 有 1 个专辑的情况。（但是 user_uid=1 的外键只是一个。而且这个问题也发生在有一对多关系的任何地方。这是我的代码..

class User(Base):
__tablename__ = 'user'

uid = Column(Integer, primary_key=True)
username = Column(String(10), unique=True, nullable=False)
email = Column(String(35), unique=True, nullable=False)
salted_password = Column(String(100), unique=True, nullable=False)
profile_pic = Column(String(100))
authorization = Column(Boolean)
expiry = Column(DATETIME)
fcm_token = Column(String(45))
created_at = Column(DATETIME)
albums = relationship('Album')
notifications = relationship('Notification')
like_photo = relationship('Photo', secondary=like_photo)
follow_album = relationship('Album', secondary=follow_album)
followed = relationship('User',
                           secondary=followers,
                           primaryjoin=(followers.c.follower_id == uid),
                           secondaryjoin=(followers.c.followed_id == uid),
                           backref=backref('followers', lazy='dynamic'),
                           lazy='dynamic')
comment_photo = relationship('Photo', secondary=comment)




class Album(Base):
__tablename__ = 'album'

aid = Column(Integer, primary_key=True)
title = Column(String(45), nullable=False)
created_at = Column(DATETIME)
user_uid = Column(Integer, ForeignKey('user.uid'))
photos = relationship('Photo')
album_tags = relationship('Album_tag')

我更新了专辑表如下..

u = User.query.filter(User.uid == session['uid']).first()
u.albums = [Album(title=request.json['title'], created_at=datetime.utcnow())]               
db_session.add(u) 
db_session.commit()

我不知道为什么..

铁拳

我相信您需要反过来做，因为按照您的方式，您正在覆盖用户的专辑列表：

coffee_album = Album(title=request.json['title'], \
                     created_at=datetime.utcnow())
u = User.query.filter(User.uid == session['uid']).first()
coffe_album.user_uid = u.uid
db_session.add(coffee_album) 
db_session.commit()

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