Laravel 5.5传递变量到子控制器返回总是null？

I have a main controller CmsController, wich is extended to default laravel controller:

use App\Http\Controllers\Controller;
class CmsController extends Controller
{
    protected $web = null;

    public function __construct(Request $request)
    {
        $this->web = Web::domain($request->domain)->first();
    }
}

Now, in this controller I want to call $this->web

use App\Http\Controllers\Web\PageController;
class PageController extends CmsController
{
    public function getPage(Request $request)
    {
        dd($this->web); // returns always null
    }
}

The data that should be returned is 100% correct, reqest params are also there...

Can someone give me a idea, what I did wrong here?

I think you need to execute parent constructor:

class PageController extends CmsController
{
    public function __construct()
    {
         parent::__construct();
         ....
    }
}

Because you can't access the session or authenticated user in your controller's constructor because the middleware has not run yet, and even if you did the dd($this->web); in the CmsController construct you will get null So you can do it like this :

use App\Http\Controllers\Controller;
class CmsController extends Controller
{
    protected $web = null;

    public function __construct()
    {
        $this->middleware(function ($request, $next) {
            $this->web = Web::domain($request->domain)->first();
            return $next($request);
        });
    }
}

You are extending CmsController and using PageController thats why ,

 use App\Http\Controllers\Web\CmsController;

 class PageController extends CmsController
 {
     public function getPage(Request $request)
     {
       dd($this->web); // returns always null
     }
 }

I have changed,

use App\Http\Controllers\Web\PageController;

to this,

use App\Http\Controllers\Web\CmsController;