有谁知道如何修复“sqlalchemy.exc.AmbiguousForeignKeysError”？

Question

sqlalchemy.exc.AmbiguousForeignKeysError：无法确定关系 Location.changes_in_location 上父/子表之间的连接条件 - 有多个外键路径链接表。指定 'foreign_keys' 参数，提供应计为包含对父表的外键引用的列的列表。

以前有人问过这个错误，但原因似乎不同。我正在尝试跟踪仓库之间的产品移动。这是我的模型文件的代码：

from inventory import db
from datetime import datetime

class Product(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), unique=True, nullable=False)
    product_movements = db.relationship('Movement', backref='item', lazy=True)

    def __repr__(self):
        return f"{self.name} added."

class Location(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), unique=True, nullable=False)
    changes_in_location = db.relationship('Movement', backref='location', lazy=True)

    def __repr__(self):
        return f"{self.location} added."

class Movement(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    product_id = db.Column(db.Integer, db.ForeignKey('product.id'))
    product = db.Column(db.String(50), nullable=False)
    from_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
    from_location = db.Column(db.String(50))
    to_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
    to_location = db.Column(db.String(50))
    quantity = db.Column(db.Integer, nullable=False)
    timestamp = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)

    def __repr__(self):
        return f"{self.quantity} units of {self.product} moved from {self.from_location} to {self.to_location} at {self.timestamp}."

Answer 1

您应该在模型中为乘法关系添加关系，并在关系中指定 ForeignKey 和 primaryjoin。

lass Location(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), unique=True, nullable=False)

    from_locations = db.relationship('Movement', backref='location', lazy=True, primaryjoin='Movement.from_location_id == Location.id')
    to_location = db.relationship('Movement', backref='location', lazy=True, primaryjoin='Movement.to_location_id == Location.id')

    def __repr__(self):
        return f"{self.location} added."

class Movement(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    product_id = db.Column(db.Integer, db.ForeignKey('product.id'))
    product = db.Column(db.String(50), nullable=False)
    from_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
    from_location = db.Column(db.String(50))
    to_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
    to_location = db.Column(db.String(50))
    quantity = db.Column(db.Integer, nullable=False)
    timestamp = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)

    from_location = db.relationship('Location', backref='from_locations', lazy=True, foreign_keys=[from_location_id])
    to_location = db.relationship('Location', backref='to_locations', lazy=True, foreign_keys=[to_location_id])

    def __repr__(self):
        return f"{self.quantity} units of {self.product} moved from {self.from_location} to {self.to_location} at {self.timestamp}."