diff --git a/file/files.go b/file/files.go
index 2bb15bc..ce86c74 100644
--- a/file/files.go
+++ b/file/files.go
@@ -82,8 +82,8 @@ func GetFilesHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	username := httpSession.Values["username"].(string)
 
-	data := map[string]interface{}{"succ": true}
-	defer util.RetGzJSON(w, r, data)
+	result := util.NewResult()
+	defer util.RetGzResult(w, r, result)
 
 	userWorkspace := conf.GetUserWorkspace(username)
 	workspaces := filepath.SplitList(userWorkspace)
@@ -118,7 +118,7 @@ func GetFilesHandler(w http.ResponseWriter, r *http.Request) {
 	// add Go API node
 	root.Children = append(root.Children, apiNode)
 
-	data["root"] = root
+	result.Data = root
 }
 
 // RefreshDirectoryHandler handles request of refresh a directory of file tree.
diff --git a/static/js/tree.js b/static/js/tree.js
index d884afa..42a0815 100644
--- a/static/js/tree.js
+++ b/static/js/tree.js
@@ -367,7 +367,7 @@ var tree = {
                             }
                         }
                     };
-                    tree.fileTree = $.fn.zTree.init($("#files"), setting, data.root.children);
+                    tree.fileTree = $.fn.zTree.init($("#files"), setting, data.data.children);
 
                     session.restore();
                 }
diff --git a/util/ret.go b/util/ret.go
index 488dc91..2989894 100644
--- a/util/ret.go
+++ b/util/ret.go
@@ -51,27 +51,15 @@ func RetResult(w http.ResponseWriter, r *http.Request, res *Result) {
 	data, err := json.Marshal(res)
 	if err != nil {
 		retLogger.Error(err)
+
 		return
 	}
 
 	w.Write(data)
 }
 
-// RetJSON writes HTTP response with "Content-Type, application/json".
-func RetJSON(w http.ResponseWriter, r *http.Request, res map[string]interface{}) {
-	w.Header().Set("Content-Type", "application/json")
-
-	data, err := json.Marshal(res)
-	if err != nil {
-		retLogger.Error(err)
-		return
-	}
-
-	w.Write(data)
-}
-
-// RetGzJSON writes HTTP response with "Content-Type, application/json".
-func RetGzJSON(w http.ResponseWriter, r *http.Request, res map[string]interface{}) {
+// RetGzResult writes HTTP response with "Content-Type, application/json" and "Content-Encoding, gzip".
+func RetGzResult(w http.ResponseWriter, r *http.Request, res *Result) {
 	w.Header().Set("Content-Type", "application/json")
 	w.Header().Set("Content-Encoding", "gzip")
 
@@ -79,6 +67,42 @@ func RetGzJSON(w http.ResponseWriter, r *http.Request, res map[string]interface{
 	err := json.NewEncoder(gz).Encode(res)
 	if nil != err {
 		retLogger.Error(err)
+
+		return
+	}
+
+	err = gz.Close()
+	if nil != err {
+		retLogger.Error(err)
+
+		return
+	}
+}
+
+// RetJSON writes HTTP response with "Content-Type, application/json".
+func RetJSON(w http.ResponseWriter, r *http.Request, res map[string]interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+
+	data, err := json.Marshal(res)
+	if err != nil {
+		retLogger.Error(err)
+
+		return
+	}
+
+	w.Write(data)
+}
+
+// RetGzJSON writes HTTP response with "Content-Type, application/json" and "Content-Encoding, gzip".
+func RetGzJSON(w http.ResponseWriter, r *http.Request, res map[string]interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Encoding", "gzip")
+
+	gz := gzip.NewWriter(w)
+	err := json.NewEncoder(gz).Encode(res)
+	if nil != err {
+		retLogger.Error(err)
+
 		return
 	}