title: Django Rest Framework partial update
body: <p>I'm trying to implement <code>partial_update</code> with <a href="http://www.django-rest-framework.org/" rel="noreferrer">Django Rest Framework</a> but I need some clarification because I'm stuck.</p>
  
  <ol>
  <li><p><strong>Why do we need to specify partial=True?</strong><br>
  In my understanding, we could easily update Demo object inside of <code>partial_update</code> method. What is the purpose of this?</p></li>
  <li><p><strong>What is inside of serialized variable?</strong><br>
  What is inside of <code>serialized</code> variable in <code>partial_update</code> method? Is that a Demo object? What function is called behind the scenes?</p></li>
  <li><strong>How would one finish the implementation here?</strong></li>
  </ol>
  
  <blockquote>
    <p>Viewset</p>
  </blockquote>
  
  <pre><code>class DemoViewSet(viewsets.ModelViewSet):
      serializer_class = DemoSerializer
  
      def partial_update(self, request, pk=None):
          serialized = DemoSerializer(request.user, data=request.data, partial=True)
          return Response(status=status.HTTP_202_ACCEPTED)
  </code></pre>
  
  <blockquote>
    <p>Serializer</p>
  </blockquote>
  
  <pre><code>class DemoSerializer(serializers.ModelSerializer):
      class Meta:
          model = Demo
          fields = '__all__'
  
      def update(self, instance, validated_data):
          print 'this - here'
          demo = Demo.objects.get(pk=instance.id)
          Demo.objects.filter(pk=instance.id)\
                             .update(**validated_data)
          return demo
  </code></pre>