laravel将数据传递到视图中（对于下拉列表）

I am trying to pass all available designations in register form as follow in laravel 5.7.21 . This is the function in RegisterController

 public function showRegistrationForm(){

$designations = Designations::all();

return view('auth.register', compact('designations'));
}

these are upper lines of RegisterController

 namespace App\Http\Controllers\Auth;

use App\User;
use App\Designation;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Facades\Validator;
use Illuminate\Foundation\Auth\RegistersUsers;

class RegisterController extends Controller

This the file structure of my project Please click here to view file structure

When I try to acces Registraion page via http://localhost:8081/register It generate a error like this please click here to view the erro

Could anyone please help me slov this hens Im new to laravel. Thanks

You spelled Designations wrong. It should be Designation::all() (as you have imported use App\Designation;).