in dynamic form list removing index not working - flutter

Question

I've recently asked a question on how to create a group of form dynamically. and i've got an answer. but the problem was when removed an index of the group it removes the last added form. but the value is correct.
for example if i add 3 dynamic group formfields and removed the second index index[1] the ui update will remove the last index but the removed value is only the selected index. why is the ui not working as expected?
import 'package:dropdown_button2/dropdown_button2.dart';
import 'package:flutter/material.dart';
class Purchased extends StatefulWidget {
const Purchased({Key? key}) : super(key: key);
#override
State<Purchased> createState() => _PurchasedState();
}
class _PurchasedState extends State<Purchased> {
List<UserInfo> list = [];
#override
Widget build(BuildContext context) {
return Scaffold(
floatingActionButton: FloatingActionButton(
onPressed: () {
/// every time you add new Userinfo, it will generate new FORM in the UI
list.add(UserInfo());
setState(() {}); // dont forget to call setState to update UI
},
child: const Icon(Icons.add),
),
body: Column(
children: [
Expanded(
child: ListView.builder(
shrinkWrap: true,
itemCount: list.length,
itemBuilder: ((context, index) {
return Column(
children: [
Text('phone'),
Text(list[index].phone),
Text('email'),
Text(list[index].email),
Text('category'),
Text(list[index].category)
],
);
})),
),
Expanded(
child: ListView.builder(
shrinkWrap: true,
itemCount: list.length,
itemBuilder: ((context, index) {
return MyForm(
// dont forget use the key, to make sure every MyForm is has identity. to avoid missed build
key: ValueKey(index),
//pass init value so the widget always update with current value
initInfo: list[index],
// every changes here will update your current list value
onChangePhone: (phoneVal) {
if (phoneVal != null) {
list[index].setPhone(phoneVal);
setState(() {});
}
},
// every changes here will update your current list value
onchangeEmail: (emailVal) {
if (emailVal != null) {
list[index].setEmail(emailVal);
setState(() {});
}
},
onchangeCategory: (categoryVal) {
if (categoryVal != null) {
list[index].setCategory(categoryVal);
setState(() {});
}
},
onremove: () {
list.removeAt(index);
setState(() {});
});
})),
)
],
),
);
}
}
class MyForm extends StatefulWidget {
final UserInfo initInfo;
final Function(String?) onChangePhone;
final Function(String?) onchangeEmail;
final Function(String?) onchangeCategory;
final VoidCallback? onremove;
const MyForm({
key,
required this.initInfo,
required this.onChangePhone,
required this.onchangeEmail,
required this.onchangeCategory,
required this.onremove,
});
#override
State<MyForm> createState() => _MyFormState();
}
class _MyFormState extends State<MyForm> {
TextEditingController _phoneCtrl = TextEditingController();
TextEditingController _emailCtrl = TextEditingController();
String? selected;
final List<String> category = [
'Manager',
'Reception',
'Sales',
'Service',
];
#override
void initState() {
super.initState();
// set init value
_phoneCtrl = TextEditingController(text: widget.initInfo.phone);
_emailCtrl = TextEditingController(text: widget.initInfo.email);
selected = widget.initInfo.category;
}
#override
Widget build(BuildContext context) {
return Container(
padding: const EdgeInsets.all(12),
child: Column(
children: [
IconButton(onPressed: widget.onremove, icon: Icon(Icons.remove)),
TextFormField(
controller: _phoneCtrl,
onChanged: widget.onChangePhone,
),
TextFormField(
controller: _emailCtrl,
onChanged: widget.onchangeEmail,
),
DropdownButtonFormField2(
//key: _key,
decoration: InputDecoration(
isDense: true,
contentPadding: EdgeInsets.zero,
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(5),
),
),
isExpanded: true,
hint: const Text(
'Select Category',
style: TextStyle(fontSize: 14),
),
icon: const Icon(
Icons.arrow_drop_down,
color: Colors.black45,
),
iconSize: 30,
buttonHeight: 60,
buttonPadding: const EdgeInsets.only(left: 20, right: 10),
items: category
.map((item) => DropdownMenuItem<String>(
value: item,
child: Text(
item,
style: const TextStyle(
fontSize: 14,
),
),
))
.toList(),
validator: (value) {
if (value == null) {
return 'Please select Catagory.';
}
},
onChanged: widget.onchangeCategory,
onSaved: widget.onchangeCategory)
/// same like TextFormField, you can create new widget below
/// for dropdown, you have to 2 required value
/// the initValue and the onchage function
],
),
);
}
}
class UserInfo {
///define
String _phone = '';
String _email = '';
String _category = '';
/// getter
String get phone => _phone;
String get email => _email;
String get category => _category;
///setter
void setPhone(String phone) {
_phone = phone;
}
void setEmail(String email) {
_email = email;
}
void setCategory(String category) {
_category = category;
}
}
any help is appreciated.