diff --git a/src/llmtuner/webui/components/data.py b/src/llmtuner/webui/components/data.py
index ab6b5de4..8e2e04bf 100644
--- a/src/llmtuner/webui/components/data.py
+++ b/src/llmtuner/webui/components/data.py
@@ -1,6 +1,6 @@
 import json
 import os
-from typing import TYPE_CHECKING, Dict, Tuple
+from typing import TYPE_CHECKING, Any, Dict, List, Tuple
 
 import gradio as gr
 
@@ -32,39 +32,36 @@ def can_preview(dataset_dir: str, dataset: list) -> "gr.Button":
     if len(dataset) == 0 or "file_name" not in dataset_info[dataset[0]]:
         return gr.Button(interactive=False)
 
-    local_path = os.path.join(dataset_dir, dataset_info[dataset[0]]["file_name"])
-    if (os.path.isfile(local_path)
-            or (os.path.isdir(local_path) and len(os.listdir(local_path)) != 0)):
+    data_path = os.path.join(dataset_dir, dataset_info[dataset[0]]["file_name"])
+    if os.path.isfile(data_path) or (os.path.isdir(data_path) and os.listdir(data_path)):
         return gr.Button(interactive=True)
     else:
         return gr.Button(interactive=False)
 
 
-def load_single_data(data_file_path):
-    with open(os.path.join(data_file_path), "r", encoding="utf-8") as f:
-        if data_file_path.endswith(".json"):
-            data = json.load(f)
-        elif data_file_path.endswith(".jsonl"):
-            data = [json.loads(line) for line in f]
+def _load_data_file(file_path: str) -> List[Any]:
+    with open(file_path, "r", encoding="utf-8") as f:
+        if file_path.endswith(".json"):
+            return json.load(f)
+        elif file_path.endswith(".jsonl"):
+            return [json.loads(line) for line in f]
         else:
-            data = [line for line in f]  # noqa: C416
-        return data
+            return list(f)
 
 
 def get_preview(dataset_dir: str, dataset: list, page_index: int) -> Tuple[int, list, "gr.Column"]:
     with open(os.path.join(dataset_dir, DATA_CONFIG), "r", encoding="utf-8") as f:
         dataset_info = json.load(f)
 
-    data_file: str = dataset_info[dataset[0]]["file_name"]
-    local_path = os.path.join(dataset_dir, data_file)
-    if os.path.isdir(local_path):
-        data = []
-        for file_name in os.listdir(local_path):
-            data.extend(load_single_data(os.path.join(local_path, file_name)))
+    data_path = os.path.join(dataset_dir, dataset_info[dataset[0]]["file_name"])
+    if os.path.isfile(data_path):
+        data = _load_data_file(data_path)
     else:
-        data = load_single_data(local_path)
+        data = []
+        for file_name in os.listdir(data_path):
+            data.extend(_load_data_file(os.path.join(data_path, file_name)))
 
-    return len(data), data[PAGE_SIZE * page_index: PAGE_SIZE * (page_index + 1)], gr.Column(visible=True)
+    return len(data), data[PAGE_SIZE * page_index : PAGE_SIZE * (page_index + 1)], gr.Column(visible=True)
 
 
 def create_preview_box(dataset_dir: "gr.Textbox", dataset: "gr.Dropdown") -> Dict[str, "Component"]: