title: Yii2 envelope single data in JSON response
body: <p>I went through offical guide and found a way to envelop JSON data like this.</p>
  
  <pre><code>use yii\rest\ActiveController;
  
  class UserController extends ActiveController
  {
      public $modelClass = 'app\models\User';
      public $serializer = [
          'class' =&gt; 'yii\rest\Serializer',
          'collectionEnvelope' =&gt; 'items',
      ];
  }
  </code></pre>
  
  <p>This works perfect when I have a collection and then I have a response like this.</p>
  
  <pre><code>{
       products:....
  }
  </code></pre>
  
  <p>But what I want to do is that i have a envelope for single data. For example if I do products/10 GET request to get.</p>
  
  <pre><code>{
      product:
  }
  </code></pre>
  
  <p>Hope somebody figured it out.</p>