app\controllers\SiteController::actionRequestPasswordReset PHP Method

    public function actionRequestPasswordReset()
    {
        $userDriver = isset(\Yii::$app->params['user_driver']) == true && empty(\Yii::$app->params['user_driver']) == false ? \Yii::$app->params['user_driver'] : 'local';
        if ($userDriver != 'local') {
            throw new BadRequestHttpException(Yii::t('walle', 'the login type does not provide security', array('loginType' => $userDriver)));
        }
        $model = new PasswordResetRequestForm();
        if ($model->load(Yii::$app->request->post()) && $model->validate()) {
            if ($model->sendEmail()) {
                Yii::$app->getSession()->setFlash('success', 'Check your email for further instructions.');
                return $this->goHome();
            } else {
                Yii::$app->getSession()->setFlash('error', 'Sorry, we are unable to reset password for email provided.');
            }
        }
        return $this->render('requestPasswordResetToken', ['model' => $model]);
    }