在服务器端数据表laravel 5中添加自动编号

I want to add auto number for my table like 1,2,3 until record end.

I use ($no + 1) which I usually use not work.

for load data work fine, But I dont know how to add auto numer please help me,

this for my Controller

public function getUser(Request $request)
{

  $columns = array(
      0 => 'auto_num',
      1 => 'add_time',
      2 => 'id'
    );

    $totalData = DataTes::count();
    $limit = $request->input('length');
    $start = $request->input('start');
    $order = $columns[$request->input('order.0.column')];
    $dir = $request->input('order.0.dir');

    if(empty($request->input('search.value'))){
        $posts = DataTes::offset($start)
                ->limit($limit)
                ->orderBy($order,$dir)
                ->get();
        $totalFiltered = DataTes::count();
    }else{
        $search = $request->input('search.value');
        $posts = DataTes::where('auto_num', 'like', "%{$search}%")
                        ->orWhere('add_time','like',"%{$search}%")
          ->orWhere('id','like',"%{$search}%")
                        ->offset($start)
                        ->limit($limit)
                        ->orderBy($order, $dir)
                        ->get();
        $totalFiltered = DataTes::where('auto_num', 'like', "%{$search}%")
                        ->orWhere('add_time','like',"%{$search}%")
          ->orWhere('id','like',"%{$search}%")
                        ->count();
    }


    $data = array();

    if($posts){
        $counter = 1;
        foreach($posts as $r){
            $nestedData['auto_num'] = $r->auto_num;
            $nestedData['add_time'] = $r->add_time;
            $nestedData['id'] = $r->id;
            $nestedData['no'] = $counter;
            $data[] = $nestedData;
            $counter++;
        }
    }

    $json_data = array(
        "draw"          => intval($request->input('draw')),
        "recordsTotal"  => intval($totalData),
        "recordsFiltered" => intval($totalFiltered),
        "data"          => $data
    );

    echo json_encode($json_data);


}

and this for my js

    $('#example1').DataTable( {
    "ordering": true,
    'autoWidth': true,

            "processing": true,
            "serverSide": true,
            "ajax": {
                "url":"<?= route('dataProcessing') ?>",
                "dataType":"json",
                "type":"POST",
                "data":{"_token":"<?= csrf_token() ?>"}
            },
            "columns":[
      {"data": "auto_num"},
      {"data": "add_time"},
      {"data": "id"},
      {"data": "no"}
            ]
        } );

I hope you can understand what I mean sorry for my bad english, I use laravel v5.6

You can do this:

if($posts){
    $counter = 1;
    foreach($posts as $r){
       $nestedData['auto_num'] = $r->auto_num;
       $nestedData['add_time'] = $r->add_time;
       $nestedData['id'] = $r->id;
       $nestedData['no'] = $counter;
       $data[] = $nestedData;
       $counter++;
   }
}

  {"data": "auto_num"},
  {"data": "add_time"},
  {"data": "id"},
  {"data": "no"}

Don't forget to add the "No" in your table header.