How to get data when logged into fb?

Question

Yii

I inserted a facebook login widget into my site. In the view, I want to get the display of the user's first and last name, but after I logged in, nothing happens.
Controller:

public function actions()
        {
            return [
        'auth' => [
          'class' => 'yii\authclient\AuthAction',
          'successCallback' => [$this, 'oAuthSuccess'],
        ],
      ];
        }
    public function oAuthSuccess($client) {
      // get user data from client
            $userAttributes = $client->getUserAttributes();
            return $this->render('say',['first_name' => $userAttributes['first_name'],'last_name' => $userAttributes['last_name'], ]);
      // do some thing with user data. for example with $userAttributes['email']
    }

View:

<?php
    use yii\helpers\Html;
    ?>
    <?= Html::encode($first_name) ?>
    <?= Html::encode($last_name) ?>