中间件无法在多个Route :: group中访问

Question

我的route.php文件中有多个Route::group，我无法访问另一个Route::group内的中间件。

以下是一个示例代码段

Route::group(['middleware' => ['web']], function () {
    //Login Routes...
    Route::get('/admin', 'AdminAuth\AuthController@showLoginForm');
    Route::get('/admin/login', 'AdminAuth\AuthController@showLoginForm');
    //Route::post('/admin/login', 'AdminAuth\AuthController@login');
    //Route::get('/admin/logout', 'AdminAuth\AuthController@logout');

    // Registration Routes...
    Route::get('admin/register', 'AdminAuth\AuthController@showRegistrationForm');
    Route::post('admin/register', 'AdminAuth\AuthController@register');

    Route::group([['middleware' => ['admin']], 'prefix' => 'admin'], function () {
        Route::get('/admin', array('uses' => 'AdminController@index'));
        Route::get('/departments', array('as' => '_departments', 'uses' => 'DepartmentController@index'));
        Route::get('/department/add', array('as' => '_department_add', 'uses' => 'DepartmentController@add'));
        Route::post('/department/add', array('as' => 'add', 'uses' => 'DepartmentController@add'));
    });
});

从上面代码Admin无法访问中间件，但如果我将Admin中间件置于最顶层Route::group，则可以使用。

现在，我使用管理中间件内部Route::group，因为外部路由组不需要检查身份验证