Improve edit form for BuildItem

- Hide the build field
- Limit the choices for StockItem (don't let user change the allocation!)

InvenTree/build/models.py

@@ -260,13 +260,13 @@ class BuildItem(models.Model):
 
         if self.stock_item is not None and self.stock_item.part is not None:
             if self.stock_item.part not in self.build.part.required_parts():
-                errors['stock_item'] = _("Selected stock item not found in BOM for part '{p}'".format(p=str(self.build.part)))
+                errors['stock_item'] = [_("Selected stock item not found in BOM for part '{p}'".format(p=self.build.part.name))]
             
         if self.stock_item is not None and self.quantity > self.stock_item.quantity:
-            errors['quantity'] = _("Allocated quantity ({n}) must not exceed available quantity ({q})".format(
+            errors['quantity'] = [_("Allocated quantity ({n}) must not exceed available quantity ({q})".format(
                 n=self.quantity,
                 q=self.stock_item.quantity
-            ))
+            ))]
 
         if len(errors) > 0:
             raise ValidationError(errors)

InvenTree/build/views.py

@@ -13,7 +13,7 @@ from django.forms import HiddenInput
 from part.models import Part
 from .models import Build, BuildItem
 from .forms import EditBuildForm, EditBuildItemForm, CompleteBuildForm
-from stock.models import StockLocation
+from stock.models import StockLocation, StockItem
 
 from InvenTree.views import AjaxView, AjaxUpdateView, AjaxCreateView, AjaxDeleteView
 
@@ -328,3 +328,25 @@ class BuildItemEdit(AjaxUpdateView):
         return {
             'info': 'Updated Build Item',
         }
+
+    def get_form(self):
+        """ Create form for editing a BuildItem.
+
+        - Limit the StockItem options to items that match the part
+        """
+
+        build_item = self.get_object()
+
+        form = super(BuildItemEdit, self).get_form()
+
+        query = StockItem.objects.all()
+        
+        if build_item.stock_item:
+            part_id = build_item.stock_item.part.id
+            query = query.filter(part=part_id)
+
+        form.fields['stock_item'].queryset = query
+
+        form.fields['build'].widget = HiddenInput()
+
+        return form