Way simpler implementation of the new endpoints

Signed-off-by: Paul Konstantin Gerke <paulkgerke@craftware.info>

api/views.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-from rest_framework import viewsets, status
+from rest_framework import viewsets
 from rest_framework.decorators import action
 from rest_framework.response import Response
 
@@ -51,39 +51,17 @@ class TimerViewSet(viewsets.ModelViewSet):
     serializer_class = serializers.TimerSerializer
     filterset_class = filters.TimerFilter
 
-    def __timer_operation(self, pk, func):
-        try:
-            timer = models.Timer.objects.get(pk=pk)
-            return func(timer)
-        except models.Timer.DoesNotExist:
-            return Response(
-                {"detail": "timer does not exist"},
-                status=status.HTTP_404_NOT_FOUND
-            )
-
     @action(detail=True, methods=['patch'])
     def stop(self, request, pk=None):
-        def do_stop(timer):
-            if not timer.active:
-                return Response(
-                    {"detail": "timer already stopped"},
-                    status=status.HTTP_412_PRECONDITION_FAILED
-                )
+        timer = self.get_object()
         timer.stop()
-            return Response({"detail": "timer stopped"})
-        return self.__timer_operation(pk, do_stop)
+        return Response(self.serializer_class(timer).data)
 
     @action(detail=True, methods=['patch'])
     def restart(self, request, pk=None):
-        def do_restart(timer):
-            if timer.active:
-                return Response(
-                    {"detail": "timer already active"},
-                    status=status.HTTP_412_PRECONDITION_FAILED
-                )
+        timer = self.get_object()
         timer.restart()
-            return Response({"detail": "timer restarted"})
-        return self.__timer_operation(pk, do_restart)
+        return Response(self.serializer_class(timer).data)
 
 
 class TummyTimeViewSet(TimerFieldSupportMixin, viewsets.ModelViewSet):