laravel auth

saya punya AdminController

 <?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class AdminController extends Controller
{

	public function __construct()
	{
		$this->middleware('auth');
	}

    public function index()
    {
    	return view('admin.dashboard');
    }
}

lalu LoginController

 <?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
class LoginController extends Controller
{

	public function __construct()
	{
		$this->middleware('guest');
	}

    public function login()
    {
    	return view('admin.login');
    }

    public function postLogin(Request $request)
    {
    	if(Auth::attempt([
    		'email' 	=> $request->username,
    		'password'	=> $request->password,
    	]))
    	{
    		return redirect('admin');
    	}
    	elseif(Auth::attempt([
    		'username'	=>$request->username,
    		'password'	=>$request->password,

    	]))
    	{
    		return redirect('admin');
    	}
    	else{
    		return "salah masukin password";
    	}
    }
}

saya mau mengarahkan kalau dia belum login akan ke redirect ke form login. mohon bantuan nya newbie. terima kasih