如何在DRF中验证更新字段?-HowtovalidateafieldonupdateinDRF?

I have a serializer for a model with a foreign key. The requirement is that on create, foreign key can be set to any existing object from the related model, but on update the related object cannot be changed. I can check this in the custom update(), but it would be more elegant to use serializer validation to check for this? But I am not sure how. Example code:

我有一个带有外键的模型的序列化器。需求是在创建时，可以将外键设置为与相关模型中的任何现有对象，但是更新相关对象时不能更改。我可以在custom update()中检查这个，但是使用serializer验证来检查这个是否更好?但我不知道该怎么做。示例代码:

class Person(models.Model):
    name = models.CharField(max_length=256)
    spouse = models.ForeignKey(Person)

class PersonSerializer(serializers.ModelSerializer):
    class Meta:
        model = Person

    # this is how I know how to do this
    def create(self, validated_data):
        try:
            spouse = Person.objects.get(pk=int(validated_data.pop('spouse')))
        except Person.DoesNotExist:
            raise ValidationError('Imaginary spouses not allowed!')
        return Person.objects.create(spouse=spouse, **validation_data)

    def update(self, person, validated_data):
        if person.spouse.pk != int(validated_data['spouse']):
            raise ValidationError('Till death do us part!')
        person.name = validation_data.get('name', person.name)
        person.save()
        return person

   # the way I want to do this
   def validate_spouse(self, value):
       # do validation magic

1 个解决方案

def validate_spouse(self, value):
    if self.instance and value != self.instance.spouse:
        raise serializers.ValidationError("Till death do us part!")
    return value

def __init__(self, *args, **kwargs):
    # Check if we're updating.
    updating = "instance" in kwargs and "data" in kwargs

    # Make sure the original initialization is done first.
    super().__init__(*args, **kwargs)

    # If we're updating, make the spouse field read only.
    if updating:
        self.fields['spouse'].read_Only= True