php - PayPal 的跟踪 ID

Question

有时 PayPal 会中断，并且不会返回 tracking_id。同时在自己的服务器上完成支付。这对我来说是个问题，因为即使付款成功，我的服务器最终在数据库表中有一个空白的 tracking_id 列，这给我带来了很多问题

如果再次发生这种情况，下面的 if 语句是否足以捕获此类事件？

if( !isset($trackingId) || empty($trackingId) || $trackingId == null || $trackingId == "" ) {

    // something is wrong

} else {

    // continue as normal

}

Answer 1

使用empty .

Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals FALSE. empty() does not generate a warning if the variable does not exist.

The following things are considered to be empty:

"" (an empty string) 
0 (0 as an integer)
0.0 (0 as a float) 
"0" (0 as a string) 
NULL 
FALSE 
array() (an empty array) 
$var; (a variable declared, but without a value)