How can I change ID from JSON automatically in setState?

January 2, 2023

How can I change "1" in busData['data'][1]['directions'] to id passed from another class? I want to make this dynamic. I have 3 cities in previous view and I want to pass it’s number automatically depending on which city I choose.

class Bus extends StatefulWidget {
  final String city;
  final int id;
  Bus(this.city, this.id);

  @override
  State<Bus> createState() => _BusState();
}

class _BusState extends State<Bus> {
  List _bus = [];


  Future<void> readJsonFile() async {
    final String res = await rootBundle.loadString('assets/bus.json');
    final busData = await json.decode(res);

    setState(() {
      _bus = busData['data'][1]['directions'];
    });
  }

My JSON looks like this:

{"data":
[{
    "city": "New York",
    "directions": [
        {
             "number": "1"        
        },
        {
             "number": "2"   
        },
        {
             "number": "3"     
        }
  },
  {
    "city": "Warsaw",
    "directions": [
        {
             "numer": "101",

Right now I am choosing manually 0 = New York or 1 = Warsaw. How can I change it? Any help?

I tried to pass id from Bus class to _BusState using `

State<Bus> createState() => _BusState(int id);

`
but I had problem with using it in _BusState class.

>Solution :

Try this,

class Bus extends StatefulWidget {
  final String city;
  final int id;
  final int number;
  Bus(this.city, this.id, this.number);

  @override
  State<Bus> createState() => _BusState();
}

class _BusState extends State<Bus> {
  List _bus = [];

  Future<void> readJsonFile() async {
    final String res = await rootBundle.loadString('assets/bus.json');
    final busData = await json.decode(res);

    setState(() {
      _bus = busData['data'][widget.number]['directions'];
    });
  }