Features: 1) Add dynamic tree prefetching for ordered and random scenarios; 2) Introduce create_ordered_tree_prefetch with depth-limiting capability;

Fixes: 1) Simplify ordering logic by consolidating expressions for both parent and child nodes;

Extra: 1) Refactor query construction for improved readability; 2) Remove redundant variable `parent_order` and `child_order`.

core/filters.py

@@ -416,18 +416,49 @@ class CategoryFilter(FilterSet):
             return queryset
 
         if field == "?":
-            parent_order = "?"
+            order_expression = "?"
-            child_order = "?"
         else:
-            parent_order = f"-{field}" if desc else field
+            order_expression = f"-{field}" if desc else field
-            child_order = parent_order
 
-        qs = queryset.order_by(parent_order).prefetch_related(None)
+        qs = queryset.order_by(order_expression).prefetch_related(None)
 
-        children_qs = (
+        def create_ordered_tree_prefetch(max_depth=10):
-            Category.objects.all().order_by(child_order) if child_order != "?" else Category.objects.all().order_by("?")
+            if field == "?":
-        )
+
-        return qs.prefetch_related(Prefetch("children", queryset=children_qs))
+                def build_random_prefetch(depth):
+                    if depth <= 0:
+                        return None
+
+                    children_qs = Category.objects.all().order_by("?")
+                    nested_prefetch = build_random_prefetch(depth - 1)
+
+                    if nested_prefetch:
+                        children_qs = children_qs.prefetch_related(nested_prefetch)
+
+                    return Prefetch("children", queryset=children_qs)
+
+                return build_random_prefetch(max_depth)
+            else:
+
+                def build_ordered_prefetch(depth):
+                    if depth <= 0:
+                        return None
+
+                    children_qs = Category.objects.all().order_by(order_expression, "tree_id", "lft")
+                    nested_prefetch = build_ordered_prefetch(depth - 1)
+
+                    if nested_prefetch:
+                        children_qs = children_qs.prefetch_related(nested_prefetch)
+
+                    return Prefetch("children", queryset=children_qs)
+
+                return build_ordered_prefetch(max_depth)
+
+        tree_prefetch = create_ordered_tree_prefetch()
+        if tree_prefetch:
+            qs = qs.prefetch_related(tree_prefetch)
+
+        return qs
 
     def filter_name(self, queryset, _name, value):
         search_results = process_query(query=value, request=self.request)["categories"]