如何修复PHP中cURL上传文件到Pangea的InvalidBodyError问题

我有一段官方文档中的curl命令：

curl -sSLX POST 'https://file-scan.aws.us.pangea.cloud/v1/scan' \
-H 'Authorization: Bearer my-token-goes here' \
-H 'Content-Type: multipart/form-data' \
-F 'request={"transfer_method":"multipart"};type=application/json' \
-F 'upload=@AnnBall.png;type=application/octet-stream'

将其改写为PHP cURL代码用于文件上传：

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://file-scan.aws.us.pangea.cloud/v1/scan');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Authorization: Bearer my-token-goes-here',
    'Content-Type: multipart/form-data',
]);
curl_setopt($ch, CURLOPT_POSTFIELDS, [
    'request' => '{"transfer_method":"multipart"}',
    'upload' => new CURLFile('AnnBall.png', 'application/octet-stream'),
]);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

echo $response = curl_exec($ch);

curl_close($ch);
?>

执行后出现以下错误：

{"request_id":"prq_nxj6w7ws5ussjsniphkzk7i3pqlf5peu","request_time":"2024-04-25T17:15:00.638627Z","response_time":"2024-04-25T17:15:01.722276Z","status":"InvalidBodyError","summary":"Failed to read request body","result":null}

问题原因及解决方法 #

核心问题

1. 手动设置Content-Type导致头部缺失boundary：PHP处理数组格式的CURLOPT_POSTFIELDS时，会自动生成带boundary分隔符的multipart/form-data头部，手动设置该字段会覆盖正确头部，导致服务端无法解析表单。
2. request字段未指定JSON类型：原始curl命令中request字段明确标注了type=application/json，但PHP默认会把字符串字段以text/plain类型发送，服务端无法识别该字段为JSON格式。

修正后的代码（PHP 8.1+推荐）

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://file-scan.aws.us.pangea.cloud/v1/scan');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Authorization: Bearer my-token-goes-here',
    // 移除手动设置的Content-Type，让PHP自动生成带boundary的头部
]);
curl_setopt($ch, CURLOPT_POSTFIELDS, [
    // 用CURLStringFile指定request字段的内容类型为application/json
    'request' => new CURLStringFile('{"transfer_method":"multipart"}', '', 'application/json'),
    'upload' => new CURLFile('AnnBall.png', 'application/octet-stream'),
]);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

$response = curl_exec($ch);
echo $response;

curl_close($ch);
?>

兼容PHP <8.1的方案

如果PHP版本低于8.1，没有CURLStringFile，可以用数组指定字段的内容和类型：

<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://file-scan.aws.us.pangea.cloud/v1/scan');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Authorization: Bearer my-token-goes-here',
]);

$postFields = [
    'request' => [
        'value' => '{"transfer_method":"multipart"}',
        'type' => 'application/json',
    ],
    'upload' => new CURLFile('AnnBall.png', 'application/octet-stream'),
];

curl_setopt($ch, CURLOPT_POSTFIELDS, $postFields);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

$response = curl_exec($ch);
echo $response;

curl_close($ch);
?>

内容的提问来源于stack exchange，提问作者Nancy Moore