Part API changes

- Allow filtering parts with null parent (top-level category parts)
- Option to include sub-category parts or not

InvenTree/InvenTree/static/script/inventree/part.js

@@ -95,6 +95,10 @@ function loadPartTable(table, url, options={}) {
         query.active = true;
     }
 
+    // Include sub-category search
+    // TODO - Make this user-configurable!
+    query.cascade = true;
+
     var columns = [
         {
             field: 'pk',

InvenTree/part/api.py

@@ -243,11 +243,24 @@ class PartList(generics.ListCreateAPIView):
         # Start with all objects
         parts_list = Part.objects.all()
 
-        if cat_id:
+        cascade = str2bool(self.request.query_params.get('cascade', False))
+
+        if cat_id is not None:
+
+            if isNull(cat_id):
+                parts_list = parts_list.filter(category=None)
+            else:
                 try:
+                    cat_id = int(cat_id)
                     category = PartCategory.objects.get(pk=cat_id)
+
+                    # If '?cascade=true' then include parts which exist in sub-categories
+                    if cascade:
                         parts_list = parts_list.filter(category__in=category.getUniqueChildren())
-            except PartCategory.DoesNotExist:
+                    # Just return parts directly in the requested category
+                    else:
+                        parts_list = parts_list.filter(category=cat_id)
+                except (ValueError, PartCategory.DoesNotExist):
                     pass
 
         # Ensure that related models are pre-loaded to reduce DB trips