diff --git a/metagpt/rag/engines/simple.py b/metagpt/rag/engines/simple.py
index d5d1fc9c4..4d47c7084 100644
--- a/metagpt/rag/engines/simple.py
+++ b/metagpt/rag/engines/simple.py
@@ -134,7 +134,7 @@ class SimpleEngine(RetrieverQueryEngine):
         query_bundle = QueryBundle(query) if isinstance(query, str) else query
 
         nodes = await super().aretrieve(query_bundle)
-        self._try_reconstruct_object(nodes)
+        self._try_reconstruct_obj(nodes)
         return nodes
 
     def add_docs(self, input_files: list[str]):
@@ -149,20 +149,18 @@ class SimpleEngine(RetrieverQueryEngine):
         """Adds objects to the retriever, storing each object's original form in metadata for future reference."""
         self._ensure_retriever_modifiable()
 
-        nodes = [
-            TextNode(
-                text=obj.rag_key(),
-                metadata={
-                    "is_obj": True,
-                    "obj_dict": obj.model_dump(),
-                    "obj_cls_name": obj.__class__.__name__,
-                    "obj_mod_name": obj.__class__.__module__,
-                },
-            )
-            for obj in objs
-        ]
+        nodes = [TextNode(text=obj.rag_key(), metadata=self._get_obj_metadata(obj)) for obj in objs]
         self._save_nodes(nodes)
 
+    def _get_obj_metadata(self, obj: RAGObject) -> dict:
+        metadata = {
+            "is_obj": True,
+            "obj_dict": obj.model_dump(),
+            "obj_cls_name": obj.__class__.__name__,
+            "obj_mod_name": obj.__class__.__module__,
+        }
+        return metadata
+
     def _ensure_retriever_modifiable(self):
         if not isinstance(self.retriever, ModifiableRAGRetriever):
             raise TypeError(f"the retriever is not modifiable: {type(self.retriever)}")
@@ -175,7 +173,7 @@ class SimpleEngine(RetrieverQueryEngine):
         self.index.insert_nodes(nodes)
 
     @staticmethod
-    def _try_reconstruct_object(nodes: list[NodeWithScore]):
+    def _try_reconstruct_obj(nodes: list[NodeWithScore]):
         """If node is object, then dynamically reconstruct object, and save object to node.metadata["obj"]."""
         for node in nodes:
             if node.metadata.get("is_obj"):