Main Idea - DECOUPLE serialization & pagination

poc_prepagination.py

class LimitOffsetPrepagination(LimitOffsetPagination):
    def __init__(self, request):
        self.request = request

    def paginate_queryset(self, queryset, postpagination=None):
        self.results = super().paginate_queryset(queryset=queryset, request=self.request)

        if postpagination:
            self.results = postpagination(self.results)

        return self.results
      
      
 class LimitOffsetPrepaginationSerializer:
    class ItemSerializer(serializers.Serializer):
        pass

    def __init__(self, prepaginator, results=None):
        if results is None:
            results = []

        self.results = results
        self.prepaginator = prepaginator

    @property
    def data(self):
        return {
            'limit': self.prepaginator.limit,
            'offset': self.prepaginator.offset,
            'count': self.prepaginator.count,
            'next': self.prepaginator.get_next_link(),
            'previous': self.prepaginator.get_previous_link(),
            'results': self.ItemSerializer(self.results, many=True).data
        }

      
# ===============================================================================

class BookingListApi(APIView):
    class Prepaginator(LimitOffsetPrepagination):
        default_limit = 10
        max_limit = 50

    class OutputSerialzier(LimitOffsetPrepaginationSerializer):
        class ItemSerializer(serializers.Serializer):
            id = serializers.IntegerField()
            
    def get(self, request, *args, **kwargs):
        prepaginator = self.Prepaginator(request=request)

        paginated_bookings = get_bookings_list(
            location=self.location,
            filters=request.GET,
            prepaginator=prepaginator
        )

        serializer = self.OutputSerialzier(results=paginated_bookings, prepaginator=prepaginator)

        return Response(serializer.data)
      
      
# ============================================================================

def get_bookings_list(
    *,
    filters: dict=None,
    prepaginator: LimitOffsetPrepagination=None
) -> QuerySetType[Booking]:
    bookings = Booking.objects.all()

    if filters:
        bookings = BookingFilterV2(params=filters, queryset=bookings).qs

    def attach_precalculated_fields(results):
        """
        Some expensive on-the-go property calculations for the results here...
        """

        return results

    if prepaginator is not None:
        return prepaginator.paginate_queryset(queryset=bookings, postpagination=attach_precalculated_fields)

    return attach_precalculated_fields(bookings)