Question

我试图用连接表定义多对多关系，但我无法使用sqlalchemy来完成它。这是我定义的模型的一个例子：

class Bar(Model):
    __tablename__ = 'bar'

    bar_id = Column(BigInteger, primary_key=True)


class Foo(Model):
    __tablename__ = 'foo'

    foo_id = Column(BigInteger, primary_key=True)
    owner_id = Column(BigInteger, nullable=False, index=True)


class FooBar(Model):
    __tablename__ = 'foo_bar'

    foo_id = Column(ForeignKey('foo.foo_id'), nullable=False, primary_key=True)
    bar_id = Column(ForeignKey('bar.bar_id'), nullable=False, primary_key=True)
    amount = Column(Integer)

    foo = relationship('Foo')
    bar = relationship('Bar')


class EnhancedBar(Model):
    __tablename__ = 'enhanced_bar'

    bar_id = Column(ForeignKey('bar.bar_id'), primary_key=True, nullable=False)
    owner_id = Column(BigInteger, primary_key=True, nullable=False, index=True)

    bar = relationship('Bar', backref=backref('enhanced_bar', uselist=False))
    foos = relationship(
        'Foo', secondary='foo_bar',
        primaryjoin="and_(EnhancedBar.bar_id==FooBar.bar_id,"
                    "Foo.owner_id==EnhancedBar.owner_id)",
        backref=backref('enchanced_bars',
            primaryjoin="and_(EnhancedBar.bar_id==FooBar.bar_id, "
                        "Foo.owner_id==EnhancedBar.owner_id)")
    )

EnhancedBar.foos关系及其backref当前工作正常，但我不确定这是否正确，因为以上是发出此查询：

SELECT *
FROM foo, foo_bar 
WHERE :param_1 = foo_bar.bar_id AND foo.ownwer_id = :param_2 AND foo.foo_id = foo_bar.foo_id

实际上，我尝试发出以下查询：

SELECT *
FROM foo JOIN foo_bar ON foo.foo_id = foo_bar.foo_id
WHERE foo.owner_id = :owner_id_param AND foo_bar.bar_id = :bar_id_param

但我无法找到如何将其转换为sqlalchemy语言。是否有任何具体的符号我应该用来实现这个目标？

SQLAlchemy定义与连接表的关系

0 个答案: