小编Rhy*_*ore的帖子

我一直在绞尽脑汁,似乎无法解决如何解决这个问题.请注意,我已从模型中删除了大量不相关的字段

我正在编写我的SQL-Alchemy模型,并遇到了以下问题:

由于多个计费系统,每个都有完全不同的属性,并且由于订阅属性的不同类型(即用户名,节点位置等),我不得不走多态继承之路.

class Subscription(Base):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(255))
    secret = db.Column(postgresql.BYTEA)
    type = db.Column(SubscriptionType.db_type())
    status = db.Column(StatusType.db_type())
    subscription_id = db.Column(db.Integer)

    __tablename__ = 'subscription'
    __table_args__ = {'schema':'public'}

    __mapper_args__ = {'polymorphic_on' : type}

    def __repr__(self):
        return '<Subscription: %r>' % self.id

class Product1(Subscription):
    __mapper_args__ = {'polymorphic_identity' : SubscriptionType.product1}    
    id = db.Column(db.Integer, db.ForeignKey('public.subscription.id'), 
        primary_key = True)
    billing_system = db.Column(
        db.Integer, 
        db.ForeignKey('public.billing_system.id')
    )

class BillingSystem(Base):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(255))
    type = db.Column(BillingSystemType.db_type())

    __tablename__ = 'billing_system'
    __table_args__ = {'schema':'public'} …