Recaptcha laravel

app\Http\Controllers\Auth\LoginController.php

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;
use Illuminate\Http\Request;
use Auth;
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');
    }
    protected function validateLogin(Request $request)
      {
          $this->validate($request, [
              $this->username() => 'required', 'password' =>  'required','g-recaptcha-response' => 'required|recaptcha',
          ]);
      }
    public function logout(Request $request)
    {
        $this->guard()->logout();

        $request->session()->flush();

        $request->session()->regenerate();

        return redirect('/login');
    }

}