Laravel 5.2 \ Illuminate \ Support \ Facades \ Auth :: logout（）或$ this-＆gt; auth-＆gt; logout（）无效

Question

我正在使用Laravel 5.2创建一个Web应用程序。我已成功登录到应用程序，但当我尝试注销时。它不允许我这样做。

当我调查时，我发现\Illuminate\Support\Facades\Auth::logout()使用dd(\Illuminate\Support\Facades\Auth::logout());返回null。我也试过$this-auth->logout();这个语句也返回null。

我没有使用默认的laravel脚手架，而是创建了我的usercontroller并做了同样的事情。

努力：

Route.php

Route::get('/', 'HomeController@index');

Route::get('logout/','UserController@logout');   

Route::group(['middleware' => ['web']], function () {
    Route::get('login/','UserController@loginForm');
    Route::post('login/','UserController@login');
    Route::get('register/','UserController@register');
    Route::post('register/','UserController@store');
    Route::get('home/',['as' => 'home', 'uses' => 'HomeController@index']); 
});

UserController.php

namespace App\Http\Controllers;

use App\User;
use App\Profile;

use Illuminate\Contracts\Auth\Guard;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;

class UserController extends Controller
{

      /**
     * User model instance
     * @var User
     */
    protected $user;
    protected $profile;

    /**
     * For Guard
     *
     * @var Authenticator
     */
    protected $auth;


    /**
     * Create a new authentication controller instance.
     *
     * @return void
     */



    public function __construct(Guard $auth, User $user)
    {
        $this->user = $user; 
        $this->auth = $auth;
        $this->middleware('guest', ['except' => 'logout']);
    }

 public function login(Request $request)
    {
        if ($this->auth->attempt($request->only('email', 'password'))) {
//            dd(\Illuminate\Support\Facades\Auth::user());
            dd(\Illuminate\Support\Facades\Auth::user());
            return redirect()->route('home');
        }

        return redirect('login')->withErrors([
            'email' => 'The email or the password is invalid. Please try again.',
        ]);
    }

    /**
     * Log the user out of the application.
     *
     * @return Response
     */
    protected function logout()
    {
//        \Illuminate\Support\Facades\Auth::logout();
        dd(\Illuminate\Support\Facades\Auth::logout());
        $this->auth->logout();
        \Session::flush();

        return redirect('login');
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function loginForm()
    {
        return view('user.login', ['title' => 'Login Page']);
    }
....
}

我很清楚为什么用户没有注销？请帮帮我。