[英]How to map multiple foreign keys to the same parent in SQLAlchemy?
将第二个外键添加到同一个表后,我收到以下错误:
Please specify the 'onclause' of this join explicitly.
如何指定这种关系?
class Parent(Base):
First = Column(Integer, ForeignKey('Child.Ex1'))
Second = Column(Integer, ForeignKey('Child.Ex2'))
class Child(Base):
Ex1 = Column(Integer)
Ex2 = Column(Integer)
(编注: pep8建议命名以小写字母开头的类属性......只是一个约定)
class Parent(Base):
__tablename__ = "Parent"
id = Column(Integer, primary_key=True)
first = Column("First", Integer, ForeignKey('Child.Ex1'))
second = Column("Second", Integer, ForeignKey('Child.Ex2'))
first_child = relationship("Child", primaryjoin="Parent.first==Child.ex1")
second_child = relationship("Child", primaryjoin="Parent.second==Child.ex2")
class Child(Base):
__tablename__ = "Child"
id = Column(Integer, primary_key=True)
ex1 = Column("Ex1", Integer)
ex2 = Column("Ex2", Integer)
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