Laravel 5.2 - Auth::login not preserve when using new \App\User - laravel

Question

I've used these code to authenticate username from external source without using database, but laravel 5.2 not save the authentication, and request the external source every time.
class Authenticate
{
public function handle($request, Closure $next, $guard = null)
{
if (Auth::guard($guard)->guest()) {
if ($request->ajax()) {
return response('Unauthorized.', 401);
} else {
$username = getFromExternalSource();
if($username==null){ redirect()->guest('auth/login'); }
$user = new \App\User(['username'=>'admin']);
Auth::login($user);
}
}
return $next($request);
}
}
But when I change Auth::login using $user model get from database it work, I don't know why:
$userDB = \App\User::where('username','=','admin')->first();
Auth::login($userDB);
My route (for example I want to access http://myApp/api)
Route::group(['middleware' => ['web']], function () {
Route::group(['middleware' => 'auth'], function () {
Route::get('api/', 'ApiController#index');
});
Route::group(['middleware' => ['csrf']], function () {
Route::controllers([
'auth' => 'Auth\AuthController',
'password' => 'Auth\PasswordController'
]);
});
});

Answer 1

As far as I know for default authenticate method, you need to pass model that exists in database. In your example you created just object and assigned to it username property.
If you need to authenticate selected user, you should use:
Auth::loginUsingId($id);
(where in place of $id you should pass id of user you want to authenticate - in your case id of user with username admin)