问Django删除模型前检查模型是否有相关对象

EN

class ModelIsDeletable(models.Model):
    name = models.CharField(max_length=200, blank=True, null=True, unique=True)
    description = models.CharField(max_length=200, blank=True, null=True)
    date_modified = models.DateTimeField(auto_now_add=True)

    def is_deletable(self):
        # get all the related object
        for rel in self._meta.get_fields():
            try:
                # check if there is a relationship with at least one related object
                related = rel.related_model.objects.filter(**{rel.field.name: self})
                if related.exists():
                    # if there is return a Tuple of flag = False the related_model object
                    return False, related
            except AttributeError:  # an attribute error for field occurs when checking for AutoField
                pass  # just pass as we dont need to check for AutoField
        return True, None

     class Meta:
        abstract = True

class StaffType(ModelIsDeletable):
    pensionable = models.BooleanField(default=False)

class Organization(ModelIsDeletable):
    staff_type = models.ForeignKey(to=StaffType)


class Department(ModelIsDeletable):
    organization = models.ForeignKey(to=Organization, to_field="id")

a_org = Organization.objects.get(pk=1)

deletable, related_obj = a_org.is_deletable()

if not deletable:
    # do some stuff with the related_obj list

else:
    # call the delete function
    a_org.delete()