Django 将字段从序列化程序传递到 model.save()，这在 model 中不存在

Question

I need to pass fields that are present in serializer, but not present in model to model save method (I have complicated saving logic and I want to make some decisions in object creation based on these fields). How can I do that? I tried to add non_db_field = property to model, but I still get error MyModel() got an unexpected keyword argument 'negative_amount'

Let's say my model is

class MyModel(AbstractModel):
    field1 = models.DateTimeField()
    field2 = models.BigIntegerField()

My serializer is

class MyModelSerializer(AbstractSerializer):
    field3 = serializers.BooleanField(required=False)

    class Meta(AbstractSerializer.Meta):
        model = MyModel
        fields = '__all__'

And my viewset is

class MyModelViewSet(AbstractViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MyModelSerializer

Answer 1

You should handle this behavior in serializer.save method, for example, you can pop it from validated_data like that:

    def save(self, **kwargs):
        self.validated_data.pop("negative_amount")

        return super().save(**kwargs)

Answer 2

You can use fields=['field1', 'field2', 'field3'] in serializer instead of fields='__all__' .

Answer 3

I found a solution based partly on Sharpek's answer and partly based on this answer:

In serializer I override save method:

    def save(self, **kwargs):
        if 'field3' in self.validated_data:
            kwargs['field3'] = self.validated_data.pop('field3')
        return super().save(**kwargs)

In models I override init method and define field:

    field3 = None
    def __init__(self, *args, **kwargs):
        if 'field3' in kwargs:
            self.field3 = kwargs.pop('field3')
        super(Reading, self).__init__(*args, **kwargs)