views.py

from django.shortcuts import get_object_or_404
from rest_framework import status, viewsets
from rest_framework.response import Response

from survey.serializers import OperatingSystemSerializer, SurveyResultSerializer
from survey.models import OperatingSystem, SurveyResult


class SurveyResultViewSet(viewsets.GenericViewSet):
    queryset = SurveyResult.objects.all()
    serializer_class = SurveyResultSerializer

    def list(self, request):
        surveys = self.get_queryset().select_related('os')
        return Response(self.get_serializer(surveys, many=True).data)

    def retrieve(self, request, pk=None):
        survey = get_object_or_404(SurveyResult, pk=pk)
        return Response(self.get_serializer(survey).data)


class OperatingSystemViewSet(viewsets.GenericViewSet):
    queryset = OperatingSystem.objects.all()
    serializer_class = OperatingSystemSerializer

    def list(self, request):
        return Response(self.get_serializer(self.get_queryset(), many=True).data)

    def retrieve(self, request, pk=None):
        try:
            os = OperatingSystem.objects.get(id=pk)
        except OperatingSystem.DoesNotExist:
            return Response(status=status.HTTP_404_NOT_FOUND)
        return Response(self.get_serializer(os).data)