例如这两个model

class A(Model):
    id = Column(Integer, primary_key=True)
    b = relationship('B', backref='a') 

class B(Model):
    id = Column(Integer, primary_key = True)
    a_id = Column(Interger, ForeignKey = "A.id")

class aAdmin(ModelView):
    column_list = ('id', 'b.id')

admin.add_view(aAdmin(A, db.session))

这样的话b.id并没有能够获取到值，那么应该如何操作呢？