refactor GridView helpers

helpers/AreaGrid.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace app\helpers;
+
+class AreaGrid extends CommonGrid {
+
+    public static function pid($departmentArray) {
+        return function($model) use ($departmentArray) {
+            return isset($departmentArray[$model->pid]) ? $departmentArray[$model->pid] : "";
+        };
+    }
+
+}