在模型中创建 Raise 错误（干净方法不起作用）

Question

我想提出一些错误，例如： 如果用户使用相同的外键创建bus_stop_1和bus_stop_2 或者如果表中对象的数量超过 4

所以我的疑问是，当我使用 clean 方法时，它无法正常工作，如何引发错误

class ConnectedRoute(models.Model):
    bus_stop_1 = models.ForeignKey(
        BusStop, on_delete=models.CASCADE, related_name='stop1')
    bus_stop_2 = models.ForeignKey(
        BusStop, on_delete=models.CASCADE, related_name='stop2')
    distance = models.FloatField(blank=True, null=True)
    time = models.TimeField(blank=True, null=True)

    def clean(self):
        if self.bus_stop_1 == self.bus_stop_2:
            raise ValidationError('Both stop cannot to the same')
        count_stop1 = ConnectedRoute.objects.filter(
            bus_stop_1=self.bus_stop_1).count()
        count_stop2 = ConnectedRoute.objects.filter(
            bus_stop_2=self.bus_stop_2).count()

        if count_stop1 + count_stop2 > 4:
            raise ValidationError('Only 4 connections allowed.')

我尝试使用这种干净的方法，但我从未发现它有用 有什么遗漏的吗

Answer 1

您必须调用 model_instance.save() 来调用 clean() 方法进行验证，或者可以手动调用 model_instance.clean() 然后 model_instance.save()

尝试重写save方法并在save中调用full_clean()。

class ConnectedRoute(models.Model):
   bus_stop_1 = models.ForeignKey(
       BusStop, on_delete=models.CASCADE, related_name='stop1')
   bus_stop_2 = models.ForeignKey(
       BusStop, on_delete=models.CASCADE, related_name='stop2')
   distance = models.FloatField(blank=True, null=True)
   time = models.TimeField(blank=True, null=True)


   def clean(self):
      if self.bus_stop_1 == self.bus_stop_2:
         raise ValidationError('Both stop cannot be the same')
      
      count_stop1 = ConnectedRoute.objects.filter(
           bus_stop_1=self.bus_stop_1).count()
      count_stop2 = ConnectedRoute.objects.filter(
           bus_stop_2=self.bus_stop_2).count()

      if count_stop1 + count_stop2 > 4:
        raise ValidationError('Only 4 connections allowed.')

   def save(self, *args, **kwargs):
      self.full_clean()
      super().save(*args, **kwargs)}