Exception Type: ProtectedError at /api/v1/spi/sites/6
Exception Value: ("Cannot delete some instances of model 'Site' because they are referenced through a protected foreign key: 'Location.site'", <QuerySet [<Location: a_location>]>)

class LocationDetail(generics.RetrieveUpdateDestroyAPIView):
    # using get_queryset().order_by('id') prevents UnorderedObjectListWarning
    queryset = Location.objects.order_by('id')
    serializer_class = LocationSerializer
    permission_classes = (SPIPermission,)

    def perform_destroy(self, instance):
        print('LocationDetail destroy() called.')
        location = self.get_object().location
        try:
            location.delete()
        except Exception as ex:
            print(ex)
            return Response({"message": "%s." % ex}, status=status.HTTP_400_BAD_REQUEST)