PHP PayPal REST API：显示项目描述（如果适用）

Question

我在下面使用paypal脚本创建付款，我希望某些商品变体可以设置为setDescription();（如果有），

目前，所有项目都会在下面的脚本中显示相同的描述（变体）：

foreach($_SESSION['products'] as $key => $cart_itm) {

    $keys = array_keys($cart_itm);
    $matches = preg_grep('~^p_alt\-variation\-\d+~i', $keys);
    //show variations if any
    if(count($matches) > 1) {
        foreach($matches as $matched_key) {
            $variations[] = $cart_itm[$matched_key];
        }
    }

    $subtotal = $cart_itm['p_price'] * $cart_itm['p_qty'];

    $item[$key] = new Item();
    $item[$key]->setName($cart_itm['p_name'])
            ->setCurrency(PAYPAL_CURRENCY)
            ->setQuantity($cart_itm['p_qty'])
            ->setDescription(implode(' / ', $variations))
            ->setPrice($cart_itm['p_price']);

    $items[] = $item[$key];
    $customData[] = $cart_itm['p_id'].':'.$cart_itm['p_qty'];

}

的print_r（$ _ SESSION [＆＃39;产品＆＃39;]）;

Array
    (
        [0] => Array
            (
                [p_name] => Motorbike Helmet G88
                [p_code] => 2102649
                [p_coverImg] => 12-1466446199-wI5qx.png
                [p_id] => 12
                [p_price] => 68.00
                [p_alt-variation-1] => Blue
                [p_alt-variation-2] => XL
                [p_qty] => 1
            )

        [1] => Array
            (
                [p_name] => Digital PH Meter
                [p_code] => 14171613
                [p_coverImg] => 4-1460428321-I1pNy.jpg
                [p_id] => 4
                [p_price] => 31.00
                [p_qty] => 2
            )

    )

如果可用，如何将商品变体传递给->setDescription()？