Flutter TextField does not follow ListTiles within ReorderableListView - flutter

Question

I'm trying to use a TextFormField within a ReorderableListView and can't seem to get the text to follow the moving ListTile. Below is a minimally modified copy of the ReorderableListView sample code that reproduces the issue. All that's added is a list of Strings and a TextFormField per ListTile.
The example includes a Text widget that tracks with the movement of the ListTile. The difference I see with Text is that it is possible to update the Text constructor in the build method of the ListTile.
Using an itemBuilder: instead of the static children: property seems to make no difference.
What am I missing here? Thanks in advance!
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: Scaffold(
appBar: AppBar(title: const Text(_title)),
body: const MyStatefulWidget(),
),
);
}
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({Key? key}) : super(key: key);
#override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
final List<int> _items = List<int>.generate(50, (int index) => index);
final List<String> _textValues = List<String>.generate(50, (int index) => '');
#override
Widget build(BuildContext context) {
final ColorScheme colorScheme = Theme.of(context).colorScheme;
final Color oddItemColor = colorScheme.primary.withOpacity(0.05);
final Color evenItemColor = colorScheme.primary.withOpacity(0.15);
return ReorderableListView(
padding: const EdgeInsets.symmetric(horizontal: 40),
children: <Widget>[
for (int index = 0; index < _items.length; index += 1)
ListTile(
key: Key('$index'),
tileColor: _items[index].isOdd ? oddItemColor : evenItemColor,
title: Text('Item ${_items[index]}: ${_textValues[index]}'),
subtitle: TextFormField(
initialValue: _textValues[index],
onChanged: (String? value) {
setState(() {
_textValues[index] = value!;
});
},
decoration: const InputDecoration(
border: OutlineInputBorder(),
),
),
),
],
onReorder: (int oldIndex, int newIndex) {
setState(() {
if (oldIndex < newIndex) {
newIndex -= 1;
}
final int item = _items.removeAt(oldIndex);
_items.insert(newIndex, item);
final String textValue = _textValues.removeAt(oldIndex);
_textValues.insert(newIndex, textValue);
});
},
);
}
}

Answer 1

It appears as though this works if I wrap the int and String in an object, and then use a single ObjectKey as the key for the ListTile. I guess the lesson here is that even if multiple lists of properties are in sync, some widgets cache or something and aren't properly rebuilt, while others are.
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
static const String _title = 'Flutter Code Sample';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: Scaffold(
appBar: AppBar(title: const Text(_title)),
body: const MyStatefulWidget(),
),
);
}
}
class Item {
int? item;
String? text;
Item(this.item, this.text);
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({Key? key}) : super(key: key);
#override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
final List<Item> _listItems =
List<Item>.generate(50, (int index) => Item(index, ''));
#override
Widget build(BuildContext context) {
final ColorScheme colorScheme = Theme.of(context).colorScheme;
final Color oddItemColor = colorScheme.primary.withOpacity(0.05);
final Color evenItemColor = colorScheme.primary.withOpacity(0.15);
return ReorderableListView(
padding: const EdgeInsets.symmetric(horizontal: 40),
children: <Widget>[
for (int index = 0; index < _listItems.length; index += 1)
ListTile(
key: ObjectKey(_listItems[index]),
tileColor:
_listItems[index].item!.isOdd ? oddItemColor : evenItemColor,
title: Text(
'Item ${_listItems[index].item}: ${_listItems[index].text}'),
subtitle: TextFormField(
initialValue: _listItems[index].text,
onChanged: (String? value) {
setState(() {
_listItems[index].text = value!;
});
},
decoration: const InputDecoration(
border: OutlineInputBorder(),
),
),
),
],
onReorder: (int oldIndex, int newIndex) {
setState(() {
if (oldIndex < newIndex) {
newIndex -= 1;
}
final Item listItem = _listItems.removeAt(oldIndex);
_listItems.insert(newIndex, listItem);
});
},
);
}
}