Changing focus of a dynamic list in flutter - flutter

Question

I have a function in flutter that opens a dialogue box with a list of text fields. The size of the list is determined by an argument to the function. I want to move focus to the next item as each is entered. I have tried creating a list of focus nodes to do this, but it doesn't work. Can someone point out what I am doing wrong. The code I have is shown below.
Future<bool> getPositions(BuildContext context, List<String> positions) async
{
int numPositions = positions.length ;
final List<FocusNode> _fNodes = new List<FocusNode>.generate(numPositions, (_) => new FocusNode()) ;
List<Widget> _widgets = new List<Widget>(numPositions) ;
for (int i = 0 ; i < numPositions ; ++i)
{
int p = i+1;
_widgets[i] = new TextField(
style: TextStyle(fontSize: 15.0),
autofocus: true,
focusNode: _fNodes[i],
controller: TextEditingController(text: positions[i]),
textInputAction: p < numPositions ? TextInputAction.next : TextInputAction.done,
onChanged: (value)
{
if (value.trim().isNotEmpty)
positions[i] = value.trim();
},
onSubmitted: (value)
{
if (value.trim().isNotEmpty)
positions[i] = value.trim();
if (p >= numPositions)
Navigator.pop(context, true);
else
_fieldFocusChange(context, _fNodes[i], _fNodes[p]);
},
);
}
return showDialog<bool>(
context: context,
barrierDismissible: false,
builder: (context)
{
return AlertDialog(
title: Text("${Config.position} names", style: TextStyle(fontSize: 15.0)),
titlePadding: EdgeInsets.all(10.0),
contentPadding: EdgeInsets.all(0.0),
content: new Container(
width: double.maxFinite,
height: 300.0,
child: ListView(
padding: const EdgeInsets.all(8.0),
children: _widgets,
),
),
actions: <Widget>[
new FlatButton(
child: const Text('CANCEL'),
onPressed: ()
{
Navigator.of(context).pop(false);
}),
new FlatButton(
child: const Text("OK"),
onPressed: ()
{
Navigator.of(context).pop(true);
}),
],
);
},
);
}
void _fieldFocusChange(BuildContext context, FocusNode currentFocus,FocusNode nextFocus)
{
currentFocus.unfocus();
FocusScope.of(context).requestFocus(nextFocus);
}

Answer 1

I suggest adding autofocus: i == 0, else every node is requesting focus on build.
Minimal Viable Example:
class Test extends StatelessWidget {
#override
Widget build(BuildContext context) {
int listLength = 4;
List<FocusNode> _focusNodes = List<FocusNode>.generate(listLength, (int index) => FocusNode());
List<Widget> textFields = List<Widget>.generate(listLength, (int index) => TextField(
controller: TextEditingController(),
focusNode: _focusNodes[index],
onSubmitted: (String value){
if (index < listLength){
_focusNodes[index+1].requestFocus();
}
},
));
return Scaffold(
body: Container(
child: ListView(
padding: const EdgeInsets.all(8.0),
children: textFields
),
),
);
}
}