FnSettings not working in deferLoading in Yajra

What I want to do is that to create a serial number in the first column of the data table and if I am not using deferloading than the above code is working. BY Using this code data is comming but data table is not working. I am using Laravel at back end. Please comment If you need any other Information that I can provide to Solve the problem.

 var table = $('#My Table').dataTable({
            "processing": true,
            "serverSide": true,
            "ajax": "{!!  route('Route')  !!}",
            "aaSorting": [[0, "desc"]],
            "deferLoading": '{{ $total }}',
            "columns": [
                {data: 'col_1', name: 'name', 'sortable': true},
                {data: 'col_2', name: 'name', 'sortable': true},
                {data: 'col_3', name: 'name', 'sortable': true},
                {data: 'col_4', name: 'name', 'sortable': true},
                {data: 'col_5', name: 'name', 'sortable': true},
                {data: 'col_6', name: 'name', 'sortable': true},
                {data: 'col_7', name: 'name', 'sortable': true},
            ],
            "lengthMenu": [
                [5, 15, 20, -1],
                [5, 15, 20, "All"] // change per page values here
            ],
            "fnRowCallback": function (nRow, aData, iDisplayIndex) {
                var oSettings = table.fnSettings();
                $("td:first", nRow).html(oSettings._iDisplayStart + iDisplayIndex + 1);
                return nRow;
            }

        });

Javascript Error : Uncaught TypeError: Cannot read property 'fnSettings' of undefined I don't know what to do.

Well I have found this also works

"fnRowCallback": function( nRow, aData, iDisplayIndex ) {
            var row = $(nRow);
            row.attr("id", 'row'+aData['0']);
            $("td:first", nRow).html(iDisplayIndex +1);
            return nRow

Update your fnRowCallback to this