在api请求中发送到服务器时，为什么我的json_encode无法正常工作

Question

我正在尝试使用CURL将数据发送到api。我从邮递员生成了php代码，如下所示：

      curl_setopt_array($curl, array(
        CURLOPT_URL => "https://sandbox.momodeveloper.mtn.com/collection/v1_0/requesttopay",
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_ENCODING => "",
        CURLOPT_MAXREDIRS => 10,
        CURLOPT_TIMEOUT => 0,
        CURLOPT_FOLLOWLOCATION => true,
        CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
        CURLOPT_CUSTOMREQUEST => "POST",
        CURLOPT_POSTFIELDS =>"{\r\n  \"amount\": \"1012.0\",\r\n  \"currency\": \"EUR\",\r\n  \"externalId\": \"Yt6sgsjak\",\r\n  \"payer\": {\r\n    \"partyIdType\": \"MSISDN\",\r\n    \"partyId\": \"46733123453\"\r\n  },\r\n  \"payerMessage\": \"G Tax Renewal\",\r\n  \"payeeNote\": \"G Tax Renewal\"\r\n}",
        CURLOPT_HTTPHEADER => array(
          "Authorization: Bearer $token",
          "X-Reference-Id: $xref",
          "X-Target-Environment: sandbox",
          "Ocp-Apim-Subscription-Key: $OcpApim",
          "Content-Type: application/json"
        ),
      ));

但是我有一种用于提交数据的表格，因此我正在考虑将CURLOPT_POSTFIELDS替换为下面的json_encode变量。

$paymentData =json_encode(array(
  "amount"=> "1200",
  "currency"=> "EUR",
  "externalId"=> "wuwyuewhhsja",
  "payer" => array(
    "partyIdType" => "MSISDN",
    "partyId " => "096152417"
  ),
  "payerMessage" => "Please enter PIN",
  "payeeNote" => "Some charge",
), JSON_FORCE_OBJECT);

我尝试了CURLOPT_POSTFIELDS => $ paymentData和CURLOPT_POSTFIELDS =>“ $ paymentData”，但是从服务器收到500错误响应。我被困住了，试图在互联网上寻找解决方案，但都无法正常工作。但是，当我回显$ paymentData时，我实际上看到的是格式正确的json结果。