public function actionDelete($id)
    {
        if (!\Yii::$app->user->can('delete'))
            throw new ForbiddenHttpException(Module::t('core', 'Access denied.'));

        if($id == 1)
            \Yii::$app->session->setFlash(
                'warning',
                \Yii::t('core', 'Node can not be deleted.')
            );
        else {
            $node = $this->findModel($id);
            // find all node childrens
            $childrens = $node->children()->all();
            $node->deleteWithChildren();
            // update deleted rubrics to 1 in all posts with rubrics are $id or $childrens ID
            $ids = $id;
            foreach($childrens as $node)
                $ids .= ',' . $node->id;
            Post::updateAll(['rubric' => 1], 'rubric IN (' . $ids . ')');
        }

        return $this->redirect(['index']);
    }