Implement Storage navigation and other helpful stuff

shimatta_kenkyusho/api/serializers.py

@@ -50,3 +50,6 @@ class DistributorSerializer(serializers.HyperlinkedModelSerializer):
     class Meta:
         model = parts_models.Distributor
         fields = '__all__'
+
+class StockIncrementDecrementSerializer(serializers.Serializer):
+	increment = serializers.IntegerField()

shimatta_kenkyusho/api/views.py

@@ -15,6 +15,7 @@ from django.utils import timezone
 from rest_framework.authtoken.views import ObtainAuthToken
 from rest_framework.authtoken.models import Token
 from rest_framework.throttling import AnonRateThrottle
+from rest_framework.decorators import action
 
 # Create your views here.
 class UserViewSet(viewsets.ReadOnlyModelViewSet):
@@ -48,6 +49,19 @@ class PartsStockViewSet(viewsets.ModelViewSet):
     serializer_class = StockSerializer
     permission_classes = [permissions.DjangoModelPermissions]
 
+    @action(detail=True, methods=['patch'], name="change-stock-count")
+    def update_stock(self, request, pk=None):
+        stock = self.get_object()
+        serializer = StockIncrementDecrementSerializer(data=request.data)
+        if serializer.is_valid():
+            increment = serializer.data['increment']
+            if stock.atomic_increment(increment):
+                return Response({'status': 'Stock updated', 'update_value': increment})
+            else:
+                return Response({'status': 'Stock not updated. Would be negative'}, status=status.HTTP_400_BAD_REQUEST)
+        else:
+            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
+
 class PartsPackageViewSet(viewsets.ModelViewSet):
     queryset = parts_models.Package.objects.all()
     serializer_class = PackageSerializer