Django-haystack как добавить фасеты с 0 совпадений при фильтрации?

class MySearchView(FacetedSearchView):
    form_class = MySearchForm
    facet_fields = ['category', 'color', 'size']
    template_name = 'products/search_result.html'
    paginate_by = 3
    context_object_name = 'object_list'

    def get_queryset(self):
        qs = super(MySearchView, self).get_queryset()
        for field in self.facet_fields:
            qs = qs.facet(field, min_doc_count=0)
        return qs