我正在使用PHP SDK for PayPal并且我成功创建了付款并返回消息，虽然我无法从documentation中弄清楚如何可靠地传递我自己的变量，这些变量将被传回我在响应URL的$ _GET字符串中。
答案 0 :(得分：1)
When payment_method is set to paypal, you can pass custom field in the transaction object. This field can hold 256 characters and you should be able to get it in $_GET string.