带有空字符串的卷曲响应。如何获取更多信息？

Question

我的行为很奇怪，我不知道如何获得有关正在发生的事情的更多信息...

我正在使用带有 NVP API 的 Paypal Express Checkout。基本上，我发送一个请求，Paypal 回复key1=value1&key2=value2...

我用 curl 发送了第一个请求，一切正常。

然后我用 curl 发送下一个请求，但 $result 是空的。但奇怪的是，如果我打印 $paypal_url 并将其复制/粘贴到浏览器中，我会得到正确的响应。

看来 curl 没有发送请求，但我不明白为什么。如何监视 curl 和 Paypal 之间的交换？或者我怎样才能获得有关正在发生的事情的更多信息？

谢谢！

//First request (fine) : Get Paypal Checkout Details
$paypal_url = $url."?VERSION=204.0&USER=".$user."&PWD=".$pwd."&SIGNATURE=".$signature."&METHOD=GetExpressCheckoutDetails&TOKEN=".$token;
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $paypal_url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_COOKIESESSION, true);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
$result = curl_exec($curl);
curl_close($curl);

//parse the result
parse_str($result);

//Check data integrity (nothing relevant)
if($ACK!="Success" || $token!=$TOKEN || $amount!=$PAYMENTREQUEST_0_AMT || $currency!=$PAYMENTREQUEST_0_CURRENCYCODE) {
    header("HTTP/1.0 402 Payment Required");
    die("Couldn't realize the payment checkout : ".$ACK."  ".$TOKEN."   required: ".$PAYMENTREQUEST_0_AMT."   ".$PAYMENTREQUEST_0_CURRENCYCODE."<br/>".$token."  payed : ".$amount."   ".$currency);
}

//Second request : Do Paypal checkout
$paypal_url = $url;
$paypal_url .= "?VERSION=204.0";
$paypal_url .= "&USER=".$user;
$paypal_url .= "&PWD=".$pwd;
$paypal_url .= "&SIGNATURE=".$signature;
$paypal_url .= "&METHOD=DoExpressCheckoutPayment";
$paypal_url .= "&TOKEN=".$token;
$paypal_url .= "&PAYERID=".$payerid;
$paypal_url .= "&PAYMENTREQUEST_0_PAYMENTACTION=Sale";
$paypal_url .= "&PAYMENTREQUEST_0_AMT=".$amount;
$paypal_url .= "&PAYMENTREQUEST_0_CURRENCYCODE=".$currency;
$paypal_url .= "&PAYMENTREQUEST_0_ITEMAMT =".$amount;

$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $paypal_url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_COOKIESESSION, true);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
$result = curl_exec($curl);
curl_close($curl);

//Display the URL and the result... But the result is missing !
die($paypal_url."\n".$result);

//If I now copy/paste the content of $paypal_url into a browser, I get the expected result.

Answer 1

在 CURL 中启用详细模式...

curl_setopt($curl, CURLOPT_VERBOSE, true);

...看看正在传输/接收的数据