Flutter 列表值未更新

Question

I am having troubles with my list not updating in flutter,i have a for loop to fill the code of the machines and in my list _machines that receives the data from the webservice it has a code in it but when i try to assign that code to my other list machineDetails it doesnt pass a value,

Here is the code:

 Future<void> _registerTime(int index) async {
try {
  setState(() {
    _loading = true;
  });

  String res = await gruposRepo.timeRegisterWorks(widget.worker.toString(),
      widget.work, widget.product, widget.task, _machines[index].vCodigo);

  print(res);

  print("MachineDetails Lenght RegisterTime: ${machineDetails.length}");

  for (int i = 0; i < _machines.length; i++) {
    print('Machines $i code: ${_machines[i].vCodigo}');
    machineDetails[i]?.code = _machines[i].vCodigo;
    print('MachineDetails $i code: ${machineDetails[i]?.code}');

    if (res == '1') {
      machineDetails[i]?.working = true;
    } else if (res == '2') {
      machineDetails[i]?.working = false;
    }
  }

  print(machineDetails[index]?.working);

  showDialog(
      context: context,
      builder: (context) {
        return AlertDialog(
          title: Text(Translations.of(context).trans('saved')),
          actions: <Widget>[
            FlatButton(
              child: Text('OK'),
              onPressed: () => Navigator.of(context).pop(),
            )
          ],
        );
      });
} catch (e) {
  this._errorMsg = e.toString();
}

setState(() {
  _loading = false;
});
}

Here is the output:

I/flutter (14487): Machines 0 code: 4

I/flutter (14487): MachineDetails 0 code: null

I/flutter (14487): Machines 1 code: 3

I/flutter (14487): MachineDetails 1 code: null

I/flutter (14487): Machines 2 code: 22

I/flutter (14487): MachineDetails 2 code: null

I/flutter (14487): Machines 3 code: 9

I/flutter (14487): MachineDetails 3 code: null

I/flutter (14487): Machines 4 code: 25

I/flutter (14487): MachineDetails 4 code: null

I/flutter (14487): Machines 5 code: 26

I/flutter (14487): MachineDetails 5 code: null

But my list machineDetails list does get updated with the lenght of _machines list:

I/flutter (14487): MachineDetails Lenght RegisterTime: 6

Thank you for your time and attention

Answer 1

machineDetails[i].code = _machines[i].vCodigo;

Answer 2

If there are no errors, I think the problem is with using machineDetails[i]?.code so check the following updated code, it might help.

 ......

  for (int i = 0; i < _machines.length; i++) {
    print('Machines $i code: ${_machines[i].vCodigo}');
    machineDetails[i]=MachineDetails(); //line added
    machineDetails[i].code = _machines[i].vCodigo; //line updated
    print('MachineDetails $i code: ${machineDetails[i]?.code}');

    ......