一個一對多的相對

Question

SQLAlchemy的關係錯誤所以我在SQLAlchemy的這一個一對多的關係（0.8）：

class Parent(Base): 

    __tablename__ = "parents" 

    cid = Column(Integer(11), primary_key = True, autoincrement = False) 
    uid = Column(Integer(11), ForeignKey('otherTable.uid', 
      ondelete = 'CASCADE'), primary_key = True) 
    ... 

    # Relationship with child 
    childs_rel = relationship("Child", backref = 'parents', 
           cascade = "all, delete-orphan") 

和

class Child(Base): 

    __tablename__ = "childs" 

    mid = Column(Integer(11), primary_key = True, autoincrement = False) 
    cid = Column(Integer(11), ForeignKey('parents.cid', 
      ondelete = 'CASCADE'), primary_key = True) 
    uid = Column(Integer(11), ForeignKey('parents.uid', 
      ondelete = 'CASCADE'), primary_key = True) 
    ... 

我可以創建這個數據庫，但是當我試圖操縱它，我得到這個錯誤：

sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join condition between parent/child tables on relationship Parent.childs_rel - 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 reference to the parent table.

我試圖指定childs_rel「foreign_keys」，但它最高審計機關沒有外鍵在父類中，這是真的......必須在孩子的類中指定，但根據SQLAlchemy的ORM文檔，關係在「一對多」相關中的「一個」中定義...

http://docs.sqlalchemy.org/en/rel_0_8/orm/relationships.html#one-to-many

您認爲在這裏發生了什麼？ Thx很多！

Answer 1

我想我知道這裏發生了什麼：

Note that you cannot define a 「composite」 foreign key constraint, that is a constraint between a grouping of multiple parent/child columns, using ForeignKey objects. To define this grouping, the ForeignKeyConstraint object must be used, and applied to the Table. The associated ForeignKey objects are created automatically.

對不起球員。無論如何，Thx！ ：d

編輯：這裏是我的那些誰需要它的解決方案：

class Child(Base): 

    __tablename__ = "childs" 

    mid = Column(Integer(11), primary_key = True, autoincrement = False) 
    cid = Column(Integer(11), primary_key = True) 
    uid = Column(Integer(11), primary_key = True) 

    __table_args__ = (ForeignKeyConstraint([cid, uid], [Parent.cid, Parent.uid]), {})