错误在Django使用过滤器(sites__id__exac =…)

I have a four classes:

我有四门课:

class A(models.Model):
    field1 = models.BooleanField(default = True)

    class Meta:
        abstract = True


class B(models.Model):
    field2 = models.BooleanField(default = True)
    sites = models.ManyToManyField(Site)

    class Meta:
        abstract = True

class C(A,B):
    field3 = models.BooleanField(default = True)

    class Meta:
        abstract = True
class A(model