'NoneType' object has no attribute 'attributes' while creating a new catalogue product in django oscar -

in views trying create new product based on product serializer based on django oscar product model.i error 'nonetype' object has no attribute 'attributes'.following below code

views.py

    serializers import categoryserializer, productserializer, productclassserializer     oscar.apps.catalogue.models import product, category, productclass   class productviewset(viewsets.modelviewset):     """     viewset viewing , editing product instances.     """     serializer_class = productserializer     queryset = product.objects.all()      # create product     def create(self, request, format=none):         data = json.loads(request.body)         serializer = productserializer(data=data)         if serializer.is_valid():             serializer.save()             return response(serializer.data, status=status.http_201_created)          return response(serializer.errors, status=status.http_400_bad_request) 

serializers.py

class productserializer(serializers.modelserializer):       class meta:         model = product 

you probably, somewhere else in code, trying access product.attributes, product equals none