title: Django REST Framework : update() based on query string parameter
body: <p>Is it possible to modify a ViewSet's update() function to update based on a query string parameter instead of a URL resource name or the request body?</p>
  
  <p>For example, I want trigger something like this:</p>
  
  <pre><code>payload = {'field' : '2'}
  r = requests.put("http://127.0.0.1:9876/job-defs?job-def-id=2", data=payload)
  </code></pre>
  
  <p>and have this update my field when job-def-id = 2.</p>
  
  <p>What I have so far is this:</p>
  
  <pre><code>class JobDefinitionsViewSet(mixins.ListModelMixin,
                          mixins.CreateModelMixin,
                          mixins.UpdateModelMixin,
                          mixins.DestroyModelMixin,
                          viewsets.GenericViewSet):
  
      serializer_class = JobDefinitionsSerializer
  
      def update(self, request, pk=None):
          job_def_id = self.request.query_params.get('job-def-id', None)
          super(JobDefinitionsViewSet, self).update(self, request, pk=job_def_id)
  
      ...
      # other unrelated code
      ...
  </code></pre>
  
  <p>I'm not too sure how to continue. 
  I want to reuse as much as the update() function from mixins.UpdateModelMixin as possible. 
  Any help is appreciated.</p>