public function actionUpdate($id)
    {
        $model = $this->findModel($id);
        if ($model->isAuthor) {
            if ($model->load(Yii::$app->request->post()) && $model->save()) {
                Yii::$app->getSession()->setFlash('success', Yii::t('article', 'Article updated.'));
                return $this->redirect(['view', 'uuid' => $model->uuid]);
            }
            return $this->render('update', ['model' => $model]);
        }
        throw new ForbiddenHttpException(Yii::t('yii', 'You are not allowed to perform this action.'));
    }