使用外键更新另一个模型库中的字段

Question

我试图更新当前模型中的布尔字段，当第二个模型中的两个量与FK相等时。

这是一对多关系，所以我需要检查外键的每个实例的两个数量是否相等。

我认为我想做的事情会奏效，但我不确定如何写它。我现在只在Python / Django工作了几个星期

class ModelA():
  model_number = models.CharField(max_length=100)
  is_true = models.BooleanField(default=False)

  def update_is_true(self, *args, **kwargs):
    disting_model = ModelB.objects.filter(
      model_number=self.model_number
    )
    pod = self.modelb_set.all()

    ordered = sum([p.ordered for p in pod])
    received = sum([p.qty_received for p in pod])

    if received >= ordered:
        self.is_true = True
        self.save()

    """
    get a count for every instance of (ordered != received) 
    for each model_number. If count = 0, set (is_true = True) 
    """



class ModelB():
  model_number = models.ForeignKey(ModelA), on_delete=models.PROTECT)
  ordered = models.IntegerField(default=0)
  received = models.IntegerField(default=0)

这是我的数据库结构。

        ModelA
id     model_number     is_true
1      1                False

        ModelB
id      modelA_id      ordered     received
1       1                 15          15
2       1                 25          25