public function actionIndex()
 {
     $this->layout = "login";
     $model = new LoginForm();
     $model->setScenario('Existing');
     // collect user input data
     if (isset($_POST['LoginForm'])) {
         $model->attributes = $_POST['LoginForm'];
         // validate user input and redirect to the previous page if valid
         if ($model->validate() && $model->loginadmin()) {
             $this->redirect($this->createAbsoluteUrl("/admin/default"));
         } else {
             $model->addError('password', Yii::t('global', 'Invalid username or password.'));
         }
     }
     // display the login form
     $this->render('index', array('model' => $model));
 }