/app/Http/Controllers/Auth/LoginController.php
namespace App\Http\Controllers\Auth;
use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;
class LoginController extends Controller
{
    /*
    |--------------------------------------------------------------------------
    | Login Controller
    |--------------------------------------------------------------------------
    |
    | This controller handles authenticating users for the application and
    | redirecting them to your home screen. The controller uses a trait
    | to conveniently provide its functionality to your applications.
    |
    */
    use AuthenticatesUsers;
    /**
     * Where to redirect users after login.
     *
     * @var string
     */
    protected $redirectTo = '/home';
    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest')->except('logout');
    }
    public function username()
    {
        return 'email';
    }
}
usernameメソッドを変更する
public function username()
    {
        return 'username';
    }
ほう、そういうことか。

 
					 
