Laravel5.5 session ？

控制器里 2个方法 第一个 生成session 在storage\framework\sessions里确实也有 也能dump
public function test051() {
session(['key' => 'value']);
Session::save();
dump(Session::all());
}

同一个控制器里 获得session dump 是null
public function test052() {
//获取session
$data = session('key');
dump($data);
}

kernel.php里也有\Illuminate\Session\Middleware\StartSession::class,
protected $middlewareGroups = [
'web' => [
\Illuminate\Session\Middleware\StartSession::class,
\App\Http\Middleware\EncryptCookies::class,
\Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
// \Illuminate\Session\Middleware\AuthenticateSession::class,
\Illuminate\View\Middleware\ShareErrorsFromSession::class,
\App\Http\Middleware\VerifyCsrfToken::class,
\Illuminate\Routing\Middleware\SubstituteBindings::class,
],
请问哪位大侠能告诉我 是什么问题获得session dump($data) 是null