frontend/widgets/views/category_view.php

<?php
    /**.
     * User: timur
     * Date: 28.01.18
     * Time: 12:43
     *
     * @var Category[] $categories
     */
    
    use artbox\weblog\models\Category;
    use yii\helpers\Html;
    use yii\helpers\Url;
    
?>
<div class="panel panel-default sidebar-menu">
    
    <div class="panel-heading">
        <h3 class="panel-title">Категории</h3>
    </div>
    
    <div class="panel-body">
        
        <?php
            $items = [];
            $url = Url::toRoute(
                [
                    'blog/index',
                ]
            );
            $items[$url] = Html::a(
                Yii::t("app", "All"),
                $url
            );
            foreach ($categories as $category){
                $url = Url::toRoute(
                    [
                        'blog/category',
                        'alias' => $category->lang->alias
                    ]
                );
                $items[$url] = Html::a(
                    $category->lang->title,
                    $url
                );
            }
            
            echo Html::ul(
                $items,
                [
                    'encode' => false,
                    'class' => "nav nav-pills nav-stacked",
                    'item' => function($item, $index){
                        $class = '';
                        if ($index === Yii::$app->request->getUrl()){
                            $class = "active";
                        }
                        
                        return "<li class={$class}>" . $item . "</li>";
                    }
                ]
            );
            
        ?>
        
    </div>
</div>