fix chatflow metadata field name (#16130)

api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py

@@ -384,7 +384,7 @@ class KnowledgeRetrievalNode(LLMNode):
     ) -> list[dict[str, Any]]:
         # get all metadata field
         metadata_fields = db.session.query(DatasetMetadata).filter(DatasetMetadata.dataset_id.in_(dataset_ids)).all()
-        all_metadata_fields = [metadata_field.field_name for metadata_field in metadata_fields]
+        all_metadata_fields = [metadata_field.name for metadata_field in metadata_fields]
         # get metadata model config
         metadata_model_config = node_data.metadata_model_config
         if metadata_model_config is None: