Laravel 5.2+ - disable registration for not admin users - php

Question

I'm trying to achieve what described here
https://www.codecourse.com/index.php/forum/topics/how-can-l-protect-the-register-page-in-laravel-52-with-the-auth-middleware-after-php-artisan-make-auth/2717
but I'm not able to get it.
Basically to prevent users that are not "admin" to register new users.
I'm really new with Laravel, so probably it's a simply thing I'm not able to get. And I know there's a lot of material on the web, but I've tried almost everything and nothing wants work.
My AuthController is:
<?php
namespace App\Http\Controllers\Auth;
use App\User;
use Validator;
use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\ThrottlesLogins;
use Illuminate\Foundation\Auth\AuthenticatesAndRegistersUsers;
class AuthController extends Controller
{
/*
|--------------------------------------------------------------------------
| Registration & Login Controller
|--------------------------------------------------------------------------
|
| This controller handles the registration of new users, as well as the
| authentication of existing users. By default, this controller uses
| a simple trait to add these behaviors. Why don't you explore it?
|
*/
use AuthenticatesAndRegistersUsers, ThrottlesLogins;
/**
* Where to redirect users after login / registration.
*
* #var string
*/
protected $redirectTo = '/';
/**
* Create a new authentication controller instance.
*
* #return void
*/
public function __construct()
{
$this->middleware($this->guestMiddleware(), ['except' => ['logout', 'getRegister']]);
}
/**
* Get a validator for an incoming registration request.
*
* #param array $data
* #return \Illuminate\Contracts\Validation\Validator
*/
protected function validator(array $data)
{
return Validator::make($data, [
'name' => 'required|max:255',
'surname' => 'required|max:255',
'email' => 'required|email|max:255|unique:users',
'password' => 'required|min:6|confirmed',
'role' => 'required|max:5',
]);
}
/**
* Create a new user instance after a valid registration.
*
* #param array $data
* #return User
*/
protected function create(array $data)
{
$is_admin='0';
if ($data['role']=='Admin') {$is_admin='1';}
return User::create([
'name' => $data['name'],
'surname' => $data['surname'],
'email' => $data['email'],
'is_admin' => $is_admin,
'password' => bcrypt($data['password']),
]);
}
/**
* Show the application registration form.
*
* #return \Illuminate\Http\Response
*/
public function getRegister()
{
if (! Auth::user()->is_admin == '1')
return abort(403);
return $this->showRegistrationForm();
}
/**
* Handle a registration request for the application.
*
* #param \Illuminate\Http\Request $request
* #return \Illuminate\Http\Response
*/
public function postRegister(Request $request)
{
if (! Auth::user()->is_admin == '1')
return abort(403);
return $this->register($request);
}
}
and my routes.php
<?php
/*
|--------------------------------------------------------------------------
| Application Routes
|--------------------------------------------------------------------------
|
| Here is where you can register all of the routes for an application.
| It's a breeze. Simply tell Laravel the URIs it should respond to
| and give it the controller to call when that URI is requested.
|
*/
Route::get('/', function () {
return view('welcome');
});
Route::get('register', 'Auth\AuthController#getRegister');
Route::post('/register', 'Auth\AuthController#postRegister');
Route::auth();
Route::get('/home', 'HomeController#index');
However the registration form is always visible also for not logged users.
Can someone please help me telling me where is my error? (and maybe how to fix it!)
Thank you a lot, M.