Django 检测同一模型中多个字段的更改

Question

我正在使用一些 javascript 库，它们不允许我传入使用 def full_name(self): 创建的 self.full_name

想知道我应该如何根据对 3 个名称字段中任何一个的更改（或创建）来更新 full_name 字段。

class Employee(models.Model):
  first_name = StringProperty(max_length=25)
  middle_name = StringProperty(max_length=25)
  last_name = StringProperty(max_length=50)

  full_name = StringProperty(max_length=100)
  # lots of Icelanders have the same first and last name...
  full_name_includes_middle_name = BooleanProperty(default=False)

现在我正在调查@receiver，created or update_fields 看起来很有希望...

@receiver(post_save, sender=Employee)
def update_full_name(sender, update_fields, created, instance, **kwargs):
  if instance.middle_name_is_part_of_full_name == True:
    if created or update_fields is 'first_name' or 'middle_name' or 'last_name':
      instance.full_name = instance.first_name + " " + instance.middle_name + " " + instance.last_name
      instance.save()
  else:
    if created or update_fields is 'first_name' or 'last_name':
      self.full_name = self.first_name + " " + self.last_name
      instance.save()

^ 但这给出了错误：

update_full_name() missing 1 required positional argument: 'update_fields'

Answer 1

在这种情况下，创建或更新操作之间没有区别。

你可以试试这个：

@receiver(pre_save, sender=Employee)
def update_full_name(sender, instance, **kwargs):
  if instance.middle_name_is_part_of_full_name == True:
      instance.full_name = f"{instance.first_name} {instance.middle_name} {instance.last_name}"
  else:
      instance.full_name = f"{instance.first_name} {instance.last_name}"