我从https://github.com/thenbrent/paypal-digital-goods-php-examples/找到了paypal数字商品脚本

但我正在寻找多个选择项目列表...例如我有story01.pdf,story02.pdf和story03.pdf . 用户可以选择并在付款完成时提供下载链接....

example-purchase.php

<select name="os0">
        <option value="Select PDF">Select PDF
        <option value="story01">story01
        <option value="story02">story02
        <option value="story03">story03
</select>
<?php $paypal->print_buy_button(); ?>
</div>

并在付款完成后 - Return.php

<?php if( isset( $_GET['PayerID'] ) ) { ?>
        <p><a href="PDF/<Item_name>.pdf" target="_top">DOWNLOAD</a></p>
    <?php } ?>

我的问题是......我找不到;如何在数组'item_name' =>' First item name '中发布所选值,

functions.php -

array( // First item
            'item_name'        => '**First item name**',
            'item_description' => 'This is a description of the first item in the cart, it costs $9.00',
            'item_amount'      => '9.00',
            'item_tax'         => '1.00',
            'item_quantity'    => 1,
            'item_number'      => 'XF100',
        ),

和返回页面上相同的pdf名称发布下载链接....