php - PHP Slim 3 中间件的不合理错误

Question

我正在尝试使用 ValidationErrorsMiddleware.php 类作为中间件，因此我将以下代码添加到我的 bootstrap/app.php 中:

$app->add(new App\Middleware\ValidationErrorsMiddleware($container));

将上述代码添加到我的 app.php 后出现以下错误:

Fatal error: Uncaught exception 'RuntimeException' with message 'Unexpected data in output buffer. Maybe you have characters before an opening <?php tag?' in C:\wamp64\www\authentication\vendor\slim\slim\Slim\App.php on line 552
RuntimeException: Unexpected data in output buffer. Maybe you have characters before an opening <?php tag? in C:\wamp64\www\authentication\vendor\slim\slim\Slim\App.php on line 552

以防万一，任何人都需要查看我的类和 app.php 的代码，我已将它们包含在此处

---

ValidationErrorsMiddleware.php

<?php

namespace App\Middleware;

class ValidationErrorsMiddleware extends Middleware {

  public function __invoke($request, $response, $next) {

    var_dump('middleware');
    $response = $next($request, $response);

    return $response;
  }
}

中间件.php

<?php

namespace App\Middleware;

class Middleware {

protected $container;

  public function __construct($container) {

    $this->container = $container;
  }
}

应用.php

<?php

session_start();

require __DIR__ . '/../vendor/autoload.php';

$app = new \Slim\App([
'settings' => [
    'determineRouteBeforeAppMiddleware' => false,
    'displayErrorDetails' => true,
    'db' => [
        // Eloquent configuration
        'driver' => 'mysql',
        'host' => 'localhost',
        'database' => 'phpdb',
        'username' => 'root',
        'password' => 'root',
        'charset' => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix' => '',
    ]
],
]);


$container = $app->getContainer();

$app->add(new App\Middleware\ValidationErrorsMiddleware($container));

require __DIR__ . '/../app/routes.php';

Answer 1

我已经解决了我的问题:

return [
'settings' => [
    // Slim Settings
    'determineRouteBeforeAppMiddleware' => true,
    'displayErrorDetails' => true,
    'addContentLengthHeader' => false,

我在设置数组中添加了值为 false 的属性 addContentLengthHeader。

但是我还是不明白这是干什么的

更新

发生此问题是因为 var_dump(middleware) 行更改了响应的内容长度。我的解决方案只是一个黑客。感谢@iKlsR 提供正确答案。