title: How can I get the model created by super().create() in a ModelViewSet?
body: <p>I'm trying to get a copy of the model created by <code>super().create()</code> in my ModelViewSet's <code>create()</code> method. What's the simplest way to do that?</p>
  
  <p>I have a ModelViewSet that takes a generic <code>POST</code> request, which I know is good because I end up with a new record in my DB. What I want to do is get the object that was just created so I can return its <code>pk</code> to the client. However, the following will not work:</p>
  
  <pre class="lang-py prettyprint-override"><code>class ItemViewSet(viewsets.ModelViewSet):
      model = Item
      # ...
      def create(self, request, *args, **kwargs):
          super().create(request, *args, **kwargs)  # Successfully creates instance
          instance = self.get_object()  # Throws error
          return Response({'status': 'success', 'pk': instance.pk})
  </code></pre>
  
  <p>Like with other DRF ModelViewSet methods, I'd expect <code>self.get_object()</code> to get me the instance created, though this is usually only usable in a "detail route". What I get instead is the following error:
  <code>AssertionError: Expected view CultivarStockViewSet to be called with a URL keyword argument named "pk". Fix your URL conf, or set the `.lookup_field` attribute on the view correctly.</code></p>
  
  <p>Any insight is appreciated!</p>