PHP cURL提交登录表单至API失败，请求排查问题

我尝试用PHP cURL把HTML表单里的邮箱和密码POST到Node.js登录接口，成功后要跳转到admin/index.php，但一直收到接口返回的{"success":"false","message":"please provide email and password"}错误，自己对cURL不熟，找不到问题，帮忙排查。

我的PHP代码： #

<?php
session_start();
// include('includes/config.php');
$error = ''; //Variable to Store error message;
if (isset($_POST['login'])) {
if (empty($_POST['email']) || empty($_POST['password'])) {
    $error = "Email or Password is Invalid";
} else {
    //Define $user and $pass
    $email = ($_POST['email']);
    $password = ($_POST['password']);

            
    $url = 'http://localhost:5000/auth/login';
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_USERPWD, $email.":".$password);
    curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode(['email' => $email, 'password' =>$password]));

    $result = curl_exec($curl);
    echo $result;


    if ($result == 200) {

        $_SESSION['alogin'] = $email;
        header("Location: admin/index.php"); // Redirecting to other page
    } else {
        $error = "Try to login.";
    }
    curl_close($curl);
}
}

?>

HTML表单： #

<div class="panel panel-info">
                        <div class="panel-heading">
                            LOGIN FORM
                        </div>
                        <div class="panel-body">
                            <form role="form" method="post" name="login" action="index.php" role="form">
                                <div class="form-group">
                                    <label>Enter Email</label>
                                    <input class="form-control" type="email" name="email" autocomplete="off" />
                                </div>
                                <div class="form-group">
                                    <label>Password</label>
                                    <input class="form-control" type="password" name="password" autocomplete="off" />
                                </div>
                                <button type="submit" name="login" class="btn btn-info">LOGIN</button>
                            </form>
                        </div>
                    </div>

你的代码存在3个核心问题，导致接口无法正确识别参数：

• 未声明JSON请求格式：你用json_encode()生成了JSON参数，但没有告诉接口请求体是JSON类型，Node.js接口默认会按表单格式解析，自然读不到JSON里的内容。
• 误用CURLOPT_USERPWD：这个选项是用来设置HTTP基础认证的账号密码，不是POST提交的业务参数，属于多余配置。
• 错误判断请求结果：curl_exec()返回的是接口的响应内容（比如你看到的JSON字符串），不是HTTP状态码，拿它和200比较永远不会成立。

修正后的PHP代码： #

<?php
session_start();
$error = '';
if (isset($_POST['login'])) {
    if (empty($_POST['email']) || empty($_POST['password'])) {
        $error = "邮箱或密码不能为空";
    } else {
        $email = $_POST['email'];
        $password = $_POST['password'];

        $url = 'http://localhost:5000/auth/login';
        $curl = curl_init($url);
        
        // 构造JSON请求体
        $postData = json_encode([
            'email' => $email,
            'password' => $password
        ]);

        curl_setopt($curl, CURLOPT_POST, true);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        // 添加JSON请求头，告知接口参数格式
        curl_setopt($curl, CURLOPT_HTTPHEADER, [
            'Content-Type: application/json',
            'Content-Length: ' . strlen($postData)
        ]);
        // 移除多余的CURLOPT_USERPWD配置
        curl_setopt($curl, CURLOPT_POSTFIELDS, $postData);

        $result = curl_exec($curl);
        // 获取真实的HTTP状态码
        $httpCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
        // 解析接口返回的JSON响应
        $response = json_decode($result, true);
        
        // 结合状态码和接口返回的success字段判断登录结果
        if ($httpCode === 200 && $response['success'] === 'true') {
            $_SESSION['alogin'] = $email;
            header("Location: admin/index.php");
            exit; // 跳转后必须终止脚本执行，避免后续代码干扰
        } else {
            // 展示接口返回的具体错误信息
            $error = $response['message'] ?? "登录失败，请重试";
        }
        curl_close($curl);
    }
}
?>

内容的提问来源于stack exchange，提问作者Tinashe C