ShoppingCartController::actionAdd PHP Method

    public function actionAdd()
    {
        if (isset($_POST['product_id']) && isset($_POST['quantity'])) {
            $product = Product::model()->findByPk($_POST['product_id']);
            if (!is_null($product)) {
                $shoppingCart = Yii::app()->customer->getShoppingCart();
                $shoppingCart->add($product->product_id, intval($_POST['quantity']));
                echo CJSON::encode(array('success' => Yii::t('shoppingcart', '<b>Success:</b> You have added <a href=":urlproduct">:productname</a> to your <a href=":urlcart">shopping cart</a>!', array(':urlproduct' => Yii::app()->createUrl('/product/view', array('id' => $_POST['product_id'])), ':productname' => $product->description->name, ':urlcart' => Yii::app()->createUrl('/shoppingCart'))), 'total' => Yii::app()->customer->getShoppingCart()->countProducts() . " " . Yii::t('shoppingCart', 'item(s)') . " - " . Yii::app()->customer->getShoppingCart()->getTotalPrice()));
            }
        }
    }