Merge pull request open5e#609 from calumbell/bugfix/v2-item-n+1

API V2: Fixed N+1 problem on `/items` endpoint

Author: augustjohnson

api_v2/views/item.py

@@ -36,6 +36,24 @@ class ItemViewSet(viewsets.ReadOnlyModelViewSet):
     serializer_class = serializers.ItemSerializer
     filterset_class = ItemFilterSet
 
+    def get_queryset(self):
+        depth = int(self.request.query_params.get('depth', 0))
+        queryset = ItemViewSet.setup_eager_loading(super().get_queryset(), self.action, depth)
+        return queryset
+
+    # Eagerly load nested resources to address N+1 problems
+    @staticmethod
+    def setup_eager_loading(queryset, action, depth):
+        if action == 'list':
+            selects = ['armor', 'weapon']
+            # Prefetch many-to-many and reverse ForeignKey relations
+            prefetches = [
+                'category', 'document', 'document__licenses',
+                'damage_immunities', 'damage_resistances', 
+                'damage_vulnerabilities', 'rarity'
+            ]
+            queryset = queryset.select_related(*selects).prefetch_related(*prefetches)
+        return queryset
 
 class ItemRarityViewSet(viewsets.ReadOnlyModelViewSet):
     """