Laravel 5.1 Session not working outside Route::get

I have some code like this and working:

Route::get('addnew',function(){         
        $user = Users::where('username','=',session('username'))->first();
        $data = $user->toArray();
        return view('layout.addnew')->with($data);
    });
Route::post('addnew', ['uses'=>'UsersController@addnew']);

With code above: session('username') not null

But, when i use this code like below:

$user = Users::where('username','=',session('username'))->first();
$data = $user->toArray();
Route::get('addnew',function() use($data){
        return view('layout.addnew')->with($data);
    });
Route::post('addnew', ['uses'=>'UsersController@addnew']);

With code above: session('username') null => so $data is non-object and code not working.

Somebody help me, please!

Thank you very much!

via Chebli Mohamed