DRF - Paginated response - append list of all ids

Question

I have a "next object" feature on my website but I use pagination. I would like add "ids" field that contains ids of all objects filtered and sorteded into the paginated response.

Everything that I tried returns only a list of current page ids.

class StandardResultsSetPagination(PageNumberPagination):
    page_size = 20
    page_size_query_param = 'page_size'
    max_page_size = 20


    def get_paginated_response(self, data, list_of_ids):
        return Response(OrderedDict([
            ('count', self.page.paginator.count),
            ('next', self.get_next_link()),
            ('previous', self.get_previous_link()),
            ('results', data),
            ('ids', list_of_ids)
        ]))

    


class RealestateViewSet(ModelViewSet):
    ...
    pagination_class = StandardResultsSetPagination

    def get_paginated_response(self, data, list_of_ids):
        """
        Return a paginated style `Response` object for the given output data.
        """
        assert self.paginator is not None
        return self.paginator.get_paginated_response(data, list_of_ids)

    def list(self, request, *args, **kwargs):
        queryset = self.filter_queryset(self.get_queryset())

        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data, list(queryset.values_list('id', flat=True)))

        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

This returns a list of 20 ids instead of all filtered objects ids.

Do you know how to do that?

Answer 1

you can subclass BaseFilterBackend to filter the queryset (coming from get_queryset()) by providing the ids , then appending the subclass to ModelViewSet.filter_backends.

It's not clear about where your ids comes from in your question (from URL parameters ? e.g. http://your_url?param1=value1), but a quick example may be like this :

from rest_framework.filters import BaseFilterBackend

class LimitQsetFilter(BaseFilterBackend):
    def filter_queryset(self, request, queryset, view):
        ids = [1,2,3,4]
        queryset = queryset.filter(pk__in=ids)
        return queryset

class RealestateViewSet(ModelViewSet):
    ...
    filter_backends = [LimitQsetFilter,]
    ...

Then you will see filtered list of object instances on pagination.