title: Update/append serializer.data in Django Rest Framework
body: <p>How can I update/append <code>serializer.data</code> in Django Rest Framework?</p>
  
  <p>data = serializer.data.update({"item": "test"}) not working</p>
  
  <p><code>return Response(serializer.data, status=status.HTTP_201_CREATED)</code></p>
  
  <p><code>serializer.data</code> is <code>&lt;class 'rest_framework.utils.serializer_helpers.ReturnDict'&gt;</code></p>