调用未定义的方法 Illuminate\Support\Facades\Gate::define()

Call to undefined method Illuminate\Support\Facades\Gate::define()

我在 Laravel 5.6

中使用 Policy

但出现此错误:

Call to undefined method Illuminate\Support\Facades\Gate::define()

我该如何解决这个问题?

protected $policies = [
        'App\Model' => 'App\Policies\ModelPolicy',
    ];

并在引导中:

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

        $gate->define('isAdmin', function ($user){
            return $user->role == 1;
        });
}

问题已解决!

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

    Gate::define('isAdmin', function ($user) {
        return $user->role == 1;
    });
}