Faceted pagination for Django Rest Framework

pagination.py

class FacetedPagination(pagination.PageNumberPagination):
    """
    If requested, will include facet information in the response

    Example response
    ```
{
    "links": {
        "next": ..,
        "previous": ..,
    },
    "count": 10000,
    "results": [..],
    "facets": {
        "color": {"red": 250, "green": 250, "blue": 500},
        "status": {"new": 250, "complete": 700, "in-progress": 50},
        ..
    }
}
    ```
    """

    page_size = 10
    page_size_query_param = "page_size"
    max_page_size = 1000

    def paginate_queryset(self, queryset, request, view=None):
        from querytools.tools import group_by_and_annotate

        facets = view.facet_fields
        facet_data = {}
        for facet in self.facet_fields:
            facet_data[facet] = group_by_and_annotate(queryset, facet, "Count")
        self.facet_data = facet_data

        return super(FacetedPagination, self).paginate_queryset(queryset, request, view)

    def get_paginated_response(self, data):
        print("get response:")
        return response.Response(
            {
                "links": {
                    "next": self.get_next_link(),
                    "previous": self.get_previous_link(),
                },
                "count": self.page.paginator.count,
                "results": data,
                "facets": self.facet_data,
            }
        )

view.py

class MyView(views.ModelView):
  ...
  facet_fields = ["color", "status"]
  ...