授权策略 Laravel 5.3，仅返回“此操作未经授权”

Question

I'm learning about the policies in Laravel 5.3 and I'm having a problem, it always returns 'This action is unauthorized'. what am I doing wrong? Here are the codes:

UserController.php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\User;

class UserController extends Controller
{
    public function index()
    {
        $this->authorize('list');

        $users = User::all();
        return $users;
    }
}

AuthServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\Facades\Gate;
use Illuminate\Foundation\Support\Providers\AuthServiceProvider as ServiceProvider;

class AuthServiceProvider extends ServiceProvider
{
    protected $policies = [
        'App\User' => 'App\Policies\UserPolicy',
    ];

    public function boot()
    {
        $this->registerPolicies();
    }
}

UserPolicy.php

<?php

namespace App\Policies;

use App\User;
use Illuminate\Auth\Access\HandlesAuthorization;

class UserPolicy
{
    use HandlesAuthorization;

    public function list(User $user)
    {
      return true;
    }
}

Answer 1

You will need to add a second argument set to the model class when calling the authorize method, otherwise how will laravel know which list method/policy to check for authorization? Other models could also have a list method/policy, hence the need for a second argument.

$this->authorize('list', User::class);