fields.py 文件源码

def contribute_to_class(self, cls, name, *args, **kwargs):
        super(SwapIntegerField, self).contribute_to_class(cls, name)
        for constraint in cls._meta.unique_together:
            if self.name in constraint:
                raise TypeError("%s can't be part of a unique constraint." % self.__class__.__name__)
        pre_save.connect(self.get_swap_objects, sender=cls)
        post_save.connect(self.save_swap_objects, sender=cls)