Python 为一个表创建多个外键时发生SqlAlchemy错误
我是新使用sqlAlchemy的人,在创建新表时遇到问题,特别是当出现指向1个表的2个外键时:Python 为一个表创建多个外键时发生SqlAlchemy错误,python,sqlalchemy,flask-sqlalchemy,Python,Sqlalchemy,Flask Sqlalchemy,我是新使用sqlAlchemy的人,在创建新表时遇到问题,特别是当出现指向1个表的2个外键时: class Offers(db.Model): __tablename__ = 'offers' id = db.Column(db.Integer, primary_key=True, autoincrement=True) contact_ign = db.Column(db.String(100)) conversion_rate = db.Column(db.F
class Offers(db.Model):
__tablename__ = 'offers'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
contact_ign = db.Column(db.String(100))
conversion_rate = db.Column(db.Float)
stock = db.Column(db.Integer)
create_date = db.Column(db.DateTime(timezone=True), default=func.now())
currency_pair = db.relationship('CurrencyPairs', backref='pair', lazy='dynamic')
class CurrencyPairs(db.Model):
__tablename__ = 'currency_pairs'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
league = db.Column(db.String(100))
pair_id = db.Column(db.Integer, db.ForeignKey('offers.id'))
want = db.relationship('Currency', backref='want', lazy='dynamic')
have = db.relationship('Currency', backref='have', lazy='dynamic')
class Currency(db.Model):
__tablename__ = 'currency'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(100), nullable=False)
poe_trade = db.Column(db.Integer, nullable=False)
poe_official = db.Column(db.String(10), nullable=False)
tier = db.Column(db.Integer, nullable=False)
want_id = db.Column(db.Integer, db.ForeignKey('currency_pairs.id'))
have_id = db.Column(db.Integer, db.ForeignKey('currency_pairs.id'))
我得到的错误是:
sqlalchemy.exc.InvalidRequestError: One or more mappers failed to initialize - can't proceed with initialization of other mappers. Triggering mapper: 'Mapper|CurrencyPairs|currency_pairs'. Original exception was: Could not determine join condition b
etween parent/child tables on relationship CurrencyPairs.want - there are multiple foreign key paths linking the tables. Specify the 'foreign_keys' argument, providing a list of those columns which should be counted as containing a foreign key refe
rence to the parent table
我尝试了不同的事情,但得到了相同的结果。
我做错了什么?
提前谢谢。我知道这是一个老问题,但我也有同样的问题。我希望能帮助别人找到答案 sqlalchemy文档中讨论了这个问题
按照您编写代码的方式,sqlalchemy无法真正理解选择哪种关系,因为您有两个相同的关系。因此,您必须向sqlalchemy描述同一个表有两个关系。我知道这是一个老问题,但我也有同样的问题。我希望能帮助别人找到答案 sqlalchemy文档中讨论了这个问题
按照您编写代码的方式,sqlalchemy无法真正理解选择哪种关系,因为您有两个相同的关系。因此,您必须向sqlalchemy说明,同一个表有两个关系。在看到post@SuperShoot的示例后,该计算可能重复,谢谢mate在看到post@SuperShoot的示例后,该计算可能重复,谢谢mate
class Offers(db.Model):
__tablename__ = 'offers'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
contact_ign = db.Column(db.String(100))
conversion_rate = db.Column(db.Float)
stock = db.Column(db.Integer)
create_date = db.Column(db.DateTime(timezone=True), default=func.now())
currency_pair = db.relationship('CurrencyPairs', backref='pair', lazy='dynamic')
class CurrencyPairs(db.Model):
__tablename__ = 'currency_pairs'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
league = db.Column(db.String(100))
pair_id = db.Column(db.Integer, db.ForeignKey('offers.id'))
want_currency = relationship("Currency", foreign_keys='[Currency.want_id]', back_populates="want_currency_pairs")
have_currency = relationship("Currency", foreign_keys='[Currency.have_id]', back_populates="have_currency_pairs")
class Currency(db.Model):
__tablename__ = 'currency'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(100), nullable=False)
poe_trade = db.Column(db.Integer, nullable=False)
poe_official = db.Column(db.String(10), nullable=False)
tier = db.Column(db.Integer, nullable=False)
want_currency_pairs = relationship(CurrencyPairs, foreign_keys="[Currency.want_id]", back_populates="want_currency")
have_currency_pairs = relationship(CurrencyPairs, foreign_keys="[Currency.have_id]", back_populates="have_currency")