dd()是laravel中非常常用的一个函数，有debug神器的称号。
但是今天与session一起使用碰到到了问题。session内容存不住。

问题复现

public function test002(Request $request){
    $request->session()->push('key','rrr');
    $info = $request->session()->get('key');
    dd($info);
}

// 输出结果
array:1 [▼
  0 => "rrr"
]

看了运行结果原以为储存成功了，但是去其他方法获取发现是null，本地使用file储存session，发现根本没有生成缓存文件，看来是被它的运行结果迷惑了。

public function test002(Request $request){
    $request->session()->push('key','rrr');
    $info = $request->session()->get('key');
    var_dump($info);
}

接下来使用这种方法，session储存成功，生成了缓存文件。

问题猜想

session()的储存放在后置的中间件中，dd()断点了，导致储存失败。

问题验证

先造一个中间件，验证dd()是否会阻断后置中间件。

public function handle($request, Closure $next)
{
    echo '前置';
    $response = $next($request);
    echo '后置';
    return $response;
}

//输出结果
前置

找到 \Illuminate\Session\Middleware\StartSession::class 这个中间件

public function handle($request, Closure $next)
{
    $this->sessionHandled = true;

    // If a session driver has been configured, we will need to start the session here
    // so that the data is ready for an application. Note that the Laravel sessions
    // do not make use of PHP "native" sessions in any way since they are crappy.
    if ($this->sessionConfigured()) {
        $request->setLaravelSession(
            $session = $this->startSession($request)
        );

        $this->collectGarbage($session);
    }

    $response = $next($request);

    // Again, if the session has been configured we will need to close out the session
    // so that the attributes may be persisted to some storage medium. We will also
    // add the session identifier cookie to the application response headers now.
    if ($this->sessionConfigured()) {
        $this->storeCurrentUrl($request, $session);

        $this->addCookieToResponse($response, $session);    //在这里进行的储存
    }

    return $response;
}