code: def process_resource(self, req, resp, resource):
          
  
          if req.content_required and resource:
              allowed = resource.deserializer_mimetypes
  
              if req.content_length in (None, 0):
                  abort(EmptyRequestBody)
              elif req.content_type not in allowed:
                  abort(ContentTypeUnsupported(allowed))
              else:
                  deserializer = self._get_deserializer(req.content_type)
                  req.deserializer = deserializer(req, resp)
docs: Process the request after routing.
  
          Deserializer selection needs a resource to determine which
          deserializers are allowed. If a deserializer is required then
          it will be initialized & added to the request object for
          further processing.