Move "build unallocate" functionality to the API

- Much much simpler now!
- Filtering is against bom_item, not part
- Fixes a bug with the new (reasonably complex) substitution framework

InvenTree/build/api.py

@@ -21,7 +21,7 @@ from InvenTree.status_codes import BuildStatus
 
 from .models import Build, BuildItem, BuildOrderAttachment
 from .serializers import BuildAttachmentSerializer, BuildSerializer, BuildItemSerializer
-from .serializers import BuildAllocationSerializer
+from .serializers import BuildAllocationSerializer, BuildUnallocationSerializer
 
 
 class BuildFilter(rest_filters.FilterSet):
@@ -184,6 +184,42 @@ class BuildDetail(generics.RetrieveUpdateAPIView):
     serializer_class = BuildSerializer
 
 
+class BuildUnallocate(generics.CreateAPIView):
+    """
+    API endpoint for unallocating stock items from a build order
+
+    - The BuildOrder object is specified by the URL
+    - "output" (StockItem) can optionally be specified
+    - "bom_item" can optionally be specified
+    """
+
+    queryset = Build.objects.none()
+
+    serializer_class = BuildUnallocationSerializer
+
+    def get_build(self):
+        """
+        Returns the BuildOrder associated with this API endpoint
+        """
+
+        pk = self.kwargs.get('pk', None)
+
+        try:
+            build = Build.objects.get(pk=pk)
+        except (ValueError, Build.DoesNotExist):
+            raise ValidationError(_("Matching build order does not exist"))
+
+        return build
+
+    def get_serializer_context(self):
+
+        ctx = super().get_serializer_context()
+        ctx['build'] = self.get_build()
+        ctx['request'] = self.request
+
+        return ctx
+
+
 class BuildAllocate(generics.CreateAPIView):
     """
     API endpoint to allocate stock items to a build order
@@ -349,6 +385,7 @@ build_api_urls = [
     # Build Detail
     url(r'^(?P<pk>\d+)/', include([
         url(r'^allocate/', BuildAllocate.as_view(), name='api-build-allocate'),
+        url(r'^unallocate/', BuildUnallocate.as_view(), name='api-build-unallocate'),
         url(r'^.*$', BuildDetail.as_view(), name='api-build-detail'),
     ])),