尝试删除记录时,依赖关系规则尝试在SQL-Alchemy中删除主键列

Question

我Userownedshare和Share表之间有多对一的关系.

当我Userownedshare从数据库中删除一个条目时,我收到以下错误:AssertionError: Dependency rule tried to blank-out primary key column 'share.ticker'

这是有道理的,因为tickerUserownedshare中的字段是Share表中的外键.但是,我无法解决如何解决此错误.我认为,我想建立一个级联删除当一个Share条目被孤立,但我不能工作了如何做到这一点,我已经阅读文档,但我刚刚结束了与不同类型的错误,所以我觉得我失去了一些东西微不足道.希望有人能帮忙,谢谢!

这是我的代码:

class Userownedshare(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    ticker = db.Column(db.String(20), db.ForeignKey('share.ticker'))
    user = db.Column(db.String, db.ForeignKey('user.username'))
    quantity = db.Column(db.Integer, nullable=False)
    dividends = db.Column(db.Float, server_default="0.0")
    triggerlevel = db.Column(db.Integer)
    smsalert = db.Column(db.Boolean)
    emailalert = db.Column(db.Boolean)
    portfolioid = db.Column(db.String(50))
    name = db.relationship('Share', backref='userownedshare' ,  foreign_keys=[ticker])

class Share(db.Model):
    id = db.Column(db.Integer)
    name = db.Column(db.String(50), nullable=False)
    ticker = db.Column(db.String(50), db.ForeignKey('userownedshare.ticker'), primary_key=True)
    tickermatch = db.relationship('Userownedshare', backref='share',  foreign_keys=[ticker])

Answer 1

好的，所以经过一些试验和错误后，我解决了。我需要增加课堂cascade="all, delete-orphan",上的tickermatch关系Share。

但我还需要添加lazy="joined"到课堂上的name关系Userownedshare

class Userownedshare(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    ticker = db.Column(db.String(20), db.ForeignKey('share.ticker'))
    user = db.Column(db.String, db.ForeignKey('user.username'))
    quantity = db.Column(db.Integer, nullable=False)
    dividends = db.Column(db.Float, server_default="0.0")
    triggerlevel = db.Column(db.Integer)
    smsalert = db.Column(db.Boolean)
    emailalert = db.Column(db.Boolean)
    portfolioid = db.Column(db.String(50))
    name = db.relationship('Share', backref='userownedshare',  foreign_keys=[ticker], lazy="joined")

class Share(db.Model):
    id = db.Column(db.Integer)
    name = db.Column(db.String(50), nullable=False)
    ticker = db.Column(db.String(50), db.ForeignKey('userownedshare.ticker'), primary_key=True)
    tickermatch = db.relationship('Userownedshare', backref='share', cascade="all, delete-orphan", lazy="joined")