getx update not trigger ui refresh in time about getx

[allasca]

should not be a problem

 onSelectedPetak(String petak) async {
    columns = [];
    rows = [];
    update(); // << update getbuilder, remove listview to 0
    List<PetakModel> data = await storageController.getDataPetak(
        selectedDatabase, petak, selectedRph);
    Map json = data[0].toJson();
    for (var e in json.entries) {
      if (disableColumns.contains(e.key)) continue;
      columns.add(DataColumn(label: Text(e.key)));
    }
    for (int i = 0; i < data.length; i++) {
      var d = data[i];
      Map j = d.toJson();
      var cell = <DataCell>[];
      for (var e in j.entries) {
        if (disableColumns.contains(e.key)) continue;
        cell.add(DataCell(Text(e.value)));
      }
      rows.add(
        DataRow(
          selected: i.isEven,
          cells: cell,
        ),
      );
    }
    update(); // << update getbuilder listview is now have a length
  }

this code work good