code: def generic_key_modelsearch(self, request, app_label, model_name):
          
          content_type = ContentType.objects.get(app_label=app_label,
                  model=model_name)
  
          model = content_type.model_class()
          model_admin = self._registry[model].__class__(model, self)
          model_admin.change_list_template = "admin/hatband/change_list.json"
          return model_admin.changelist_view(request)
docs: Find instances for the requested model and return them as JSON.
          # TODO: add test coverage for this
  
          We don't have to worry about invalid app_label/model_name parameters
          because the URLs are pre-built with the kwargs in `get_urls()`.