【EC-CUBE3】商品詳細ページからカートボタンを押した後の在庫数を取得するイベント

SampleEvent.php

<?php

/*
 * This file is part of the Sample
 *
 * Copyright (C) 2017 サンプルプラグイン for EC-CUBE3
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Plugin\Sample;

use Eccube\Application;
use Eccube\Event\EventArgs;

class SampleEvent
{
    /** @var  \Eccube\Application $app */
    private $app;

    public function __construct(Application $app)
    {
        $this->app = $app;

    }

    /**
     * 商品詳細ページからカートボタンを押した時
     * 
     * @param EventArgs $event
     */
    public function onFrontProductDetailComplete(EventArgs $event)
    {
        $form = $event->getArgument('form');
        $addCartData = $form->getData();
        $quantity = $this->app['eccube.service.cart']->getProductQuantity($addCartData["product_class_id"]);

        echo $quantity;
    }
}