Django Rest Framework: Dynamically return subset of fields

You can override the serializer __init__ method and set the fields attribute dynamically, based on the query params. You can access the request object throughout the context, passed to the serializer.

Here is a copy&paste from Django Rest Framework documentation example on the matter:

from rest_framework import serializers

class DynamicFieldsModelSerializer(serializers.ModelSerializer):
    """
    A ModelSerializer that takes an additional `fields` argument that
    controls which fields should be displayed.
    """

    def __init__(self, *args, **kwargs):
        # Instantiate the superclass normally
        super(DynamicFieldsModelSerializer, self).__init__(*args, **kwargs)

        fields = self.context['request'].query_params.get('fields')
        if fields:
            fields = fields.split(',')
            # Drop any fields that are not specified in the `fields` argument.
            allowed = set(fields)
            existing = set(self.fields.keys())
            for field_name in existing - allowed:
                self.fields.pop(field_name)


class UserSerializer(DynamicFieldsModelSerializer, serializers.HyperlinkedModelSerializer):

    class Meta:
        model = User
        fields = ('url', 'username', 'email')

This functionality is available from a 3rd-party package.

pip install djangorestframework-queryfields

Declare your serializer like this:

from rest_framework.serializers import ModelSerializer
from drf_queryfields import QueryFieldsMixin

class MyModelSerializer(QueryFieldsMixin, ModelSerializer):
    ...

Then the fields can now be specified (client-side) by using query arguments:

GET /identities/?fields=id,data

Exclusion filtering is also possible, e.g. to return every field except id:

GET /identities/?fields!=id

disclaimer: I'm the author/maintainer.