How to select item from nested ListView.builder - flutter

Question

I'm trying to select nested listview item, used listbuilder inside a listbuilder. Let’s say, I have 10 customers with 5 orders each, want to display customer1 and 5 orders, customer2 all orders…. .
I read the records from PostgreSQL and group them based on cust_id, resulted dataType is Map<String, List> and able to display on the screen. However while selecting the orders for processing (order2 of customer1, order4 of customer2, etc) it is throwing "Unsupported operation: Cannot modify an unmodifiable list".
Looks like I’m trying to modify immutable object. I tried to change Map<String, List> to Map<String, List< DetailedPositions>> but facing another error. Can you help to select orders. Any help would be appreciated.
import 'package:flutter/material.dart';
import 'package:e2/Models/model_positions.dart';
import 'package:e2/pages/modify_order.dart';
class ModifyPosition extends StatefulWidget {
const ModifyPosition({super.key});
#override
State<ModifyPosition> createState() => _ModifyPositionState();
}
class _ModifyPositionState extends State<ModifyPosition> {
Map data = {};
List<DetailedPositions> selectedContacts = [];
List<GroupedPositions> detailedPositions = [];
#override
Widget build(BuildContext context) {
data = ModalRoute.of(context)?.settings.arguments as Map;
var custIDs = data.values.toList()[0];
var custNames = data.values.toList()[1];
return Scaffold(
appBar: AppBar(
title: Text('Modify Positions '),
centerTitle: true,
),
body: SafeArea(
child: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: [
Expanded(
child: FutureBuilder<Map<String, List<dynamic>>>(
future: ModelsPositions().detailedPositionsData(custIDs),
builder: (context, snapshot) {
Map<String, List<dynamic>> positions_raw =
snapshot.data ?? {};
List<GroupedPositions> detailedPositions = [];
positions_raw.forEach((k, v) {
detailedPositions
.add(GroupedPositions(custID: k, custInfo: v));
});
switch (snapshot.connectionState) {
case ConnectionState.waiting:
return Center(child: CircularProgressIndicator());
default:
if (snapshot.hasError) {
return Center(
child: Text(
'Error while loading Master Positions screen'));
} else {
return DetailedPosition(detailedPositions);
}}},)),],),),),);}
Widget DetailedPosition(List<GroupedPositions> detailedPositions) {
return Container(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Expanded(
child: ListView.builder(
shrinkWrap: true,
physics: BouncingScrollPhysics(),
itemCount: detailedPositions.length,
itemBuilder: (BuildContext context, int index) {
final pos = detailedPositions[index];
final ID = pos.custID;
final custInfo = pos.custInfo;
final custID = ID.split(',')[0];
final custName = ID.split(',')[1];
return Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
//Text('Parent'),
Row(children: [
Expanded(
child: Padding(
padding: EdgeInsets.all(20),
child: Text("Cust_id : $custID",
style: TextStyle(
height: 3.0,
fontSize: 15.0,
fontWeight: FontWeight.bold,
)))),
Expanded(
child: Text("Cust_Name : $custName",
style: TextStyle(
height: 3.0,
fontSize: 15.0,
fontWeight: FontWeight.bold,
))),
]),
ListView.builder(
itemCount: custInfo.length,
physics: ClampingScrollPhysics(),
shrinkWrap: true,
itemBuilder: (BuildContext context, int childIndex) {
final pos = custInfo[childIndex];
final quantity = pos.elementAt(2);
final instrument = pos.elementAt(3);
final avgPrice = pos.elementAt(4);
final prodType = pos.elementAt(5);
final price1 = pos.elementAt(6);
final price2 = pos.elementAt(7);
final isSelected = pos.elementAt(8);
return ListTile(
horizontalTitleGap: -5,
title: Card(
child: Row(
crossAxisAlignment:
CrossAxisAlignment.center,
children: [
Expanded(
child: Column(
crossAxisAlignment:
CrossAxisAlignment.stretch,
children: [
Text('Qty : $quantity'),
const SizedBox(height: 10),
Text(instrument),
const SizedBox(height: 10),
Text('Avg : $avgPrice'),
],
),
),
Flexible(
fit: FlexFit.tight,
child: Column(
mainAxisAlignment:
MainAxisAlignment.end,
crossAxisAlignment:
CrossAxisAlignment.end,
mainAxisSize: MainAxisSize.min,
children: [
Text('$prodType'),
Text('$price1'),
const SizedBox(height: 10,),
Text('$price2'), ], ), ), ])),
leading: isSelected
? Icon(
Icons.check_circle,
color: Colors.green[700],
)
: Icon(
Icons.check_circle_outline,
color: Colors.grey,
),
onTap: () {
setState(() {
detailedPositions[index].custInfo[childIndex][8] =
!detailedPositions[index].custInfo[childIndex][8]; **--> Here facing the issue**
// if (detailedPositions[index]
// .custInfo[childIndex][8] ==
// true) {
.....
});
},); }), ], ); }), ) ], ), ); } }
class DetailedPositions {
String custID;
String custName;
int quantity;
String instrument;
double avgPrice;
String prodType;
double price1;
double price2;
bool isSelected = false;
DetailedPositions(
{required this.custID,
required this.custName,
required this.quantity,
required this.instrument,
required this.avgPrice,
required this.prodType,
required this.price1,
required this.price2});
}
class GroupedPositions {
String custID;
List<dynamic> custInfo;
GroupedPositions({required this.custID, required this.custInfo});
}