filterset_field ignored

[Benjamin hansen]

Hi, I have this API:

```py

class OrderListApi(generics.ListAPIView):

    serializer_class = OrderSerializer

    model = serializer_class.Meta.model

    pagination_class = StandardResultsSetPagination

    permission_classes = [IsAuthenticated]

    filter_backends = (filters.DjangoFilterBackend,)

    filterset_fields = ('order_number',)

    def get_queryset(self, *args, **kwargs):

        current_company = self.request.user.staff.company

        who = list(current_company.clients.values_list('id', flat=True))

        who = Company.nd_objects.filter(id__in=who)

        ords = self.model.nd_objects.filter(owner__in=who)

        return self.filter_queryset(ords).order_by('-order_number')

```

which pulls data our of database nicely, however for some reason the `filterset_fields = ('order_number',)` is totally ignored, so when i pull `/api/v1/orders/list/?page=1` i get the same result as when i do `/api/v1/orders/list/?page=1&order_number=1046` What am I missing here?