Change a field in a Django REST Framework ModelSerializer based on the request type?

Question

Consider this case where I have a Book and Author model.

serializers.py

class AuthorSerializer(serializers.ModelSerializer):

         


        

Answer 1

I know it's a little late, but just in case someone else needs it. There are some third party packages for drf that allow dynamic setting of included serializer fields via the request query parameters (listed in the official docs: https://www.django-rest-framework.org/api-guide/serializers/#third-party-packages).

IMO the most complete ones are:

1. https://github.com/AltSchool/dynamic-rest
2. https://github.com/rsinger86/drf-flex-fields

where (1) has more features than (2) (maybe too many, depending on what you want to do).

With (2) you can do things such as (extracted from the repo's readme):

class CountrySerializer(FlexFieldsModelSerializer):
    class Meta:
        model = Country
        fields = ['name', 'population']


class PersonSerializer(FlexFieldsModelSerializer):
    country = serializers.PrimaryKeyRelatedField(read_only=True)

    class Meta:
        model = Person
        fields = ['id', 'name', 'country', 'occupation']

    expandable_fields = {
        'country': (CountrySerializer, {'source': 'country', 'fields': ['name']})
    }

The default response:

{
  "id" : 13322,
  "name" : "John Doe",
  "country" : 12,
  "occupation" : "Programmer"
}

When you do a GET /person/13322?expand=country, the response will change to:

{
  "id" : 13322,
  "name" : "John Doe",
  "country" : {
    "name" : "United States"
  },
  "occupation" : "Programmer",
}

Notice how population was ommitted from the nested country object. This is because fields was set to ['name'] when passed to the embedded CountrySerializer.

This way you can keep your POST requests including just an id, and "expand" GET responses to include more details.