Using regular expressions in URL rules

One of the hidden features of the Yii URL router is that you can use regular expressions that are pretty powerful for handling strings.

Getting ready

1. Create a new application using the Composer package manager, as described in the official guide at http://www.yiiframework.com/doc-2.0/guide-start-installation.html.

2. In your @app/controllers directory, create PostController.php using the following:

   <?php
   
   namespace app\controllers;
   
   use yii\helpers\Html;
   use yii\web\Controller;
   
   class PostController extends Controller
   {
       public function actionView($alias)
       {
           return $this->renderContent(Html::tag('h2',
               'Showing post with alias ' . Html::encode($alias)
           ));
       }
   
       public function actionIndex($type = 'posts', $order = 'DESC')
      {
           return $this->renderContent(Html::tag('h2',
              'Showing ' . Html::encode($type) . ' ordered ' . Html::encode($order)
           ));
       }
   
       public function actionHello($name...