laravel 6 use username instead of id code example

Example: laravel 6 use username instead of id

// using User->username instead of id on url:
public function show($user)
    {
  		// where<YourAtributeName>($param)->firstOrFail()
        $user = User::whereUsername($user)->firstOrFail();
        return view('users.show', ['user'=>$user]);
    }