Django DRF - Different Request and Response Serialization

Question

I;ve an API endpoint that requests data in the below format:-

{
  "platform": "value",
  "username": "value",
  "login_type": "value"
}

Now, I've a model :-

class ModelA(models.Model):
    field1 = models.IntegerField()

The request variables are not the part of the model, hence I create the following serializer:-

class ModelASerializer(serializers.ModelSerializer):
    username = serializers.CharField()
    login_type = serializers.IntegerField()
    platform = serializers.ChoiceField(choices=User.PLATFORM_CHOICES)

    def create(self, data):
        platform, username = data.get('platform'), data.get('username')
        login_type = data.get('login_type')
        ###### some processing based on above input
        instance = ModelA.objects.create(field1=11111)
        return instance

    class Meta:
        model = ModelA
        fields = ('username', 'login_type', 'platform')
        read_only_fields = ('field1', )

When I POST the data, the error returned back is

The serializer field might be named incorrectly and not match any attribute or key on the `ModelA` instance.
Original exception text was: 'ModelA' object has no attribute 'username'.

I understand that it tries to get_attr the fields from the instance object. How do I send back the response where INPUT request is different(ie unrelated to the model fields) and response is different(ie related to the model fields)?

Answer 1

I solved the above problem settings field as write_only = True.

class ModelASerializer(serializers.ModelSerializer):
    username = serializers.CharField(write_only = True)
    login_type = serializers.IntegerField(write_only = True)
    platform = serializers.ChoiceField(choices=User.PLATFORM_CHOICES, write_only = True)