How to detect user has stopped typing in TextField? - flutter

Question

I am using a TextField under which onChanged function
I am calling my code but the issue right now is the code gets execute everytime a new word is either entered or deleted.
what I am looking for is how to recognize when a user has stopped typing.
means adding some delay or something like that.
I have tried adding delay also using Future.delayed function but that function also gets executed n number of times.
TextField(
controller: textController,
onChanged: (val) {
if (textController.text.length > 3) {
Future.delayed(Duration(milliseconds: 450), () {
//code here
});
}
setState(() {});
},
)

Answer 1

Thanks to #pskink
I was able to achieve the functionality I was looking for.
import stream_transform package in your pubspec.yaml
stream_transform: ^0.0.19
import 'package:stream_transform/stream_transform.dart';
StreamController<String> streamController = StreamController();
#override
void initState() {
streamController.stream
.transform(debounce(Duration(milliseconds: 400)))
.listen((s) => _validateValues());
super.initState();
}
//function I am using to perform some logic
_validateValues() {
if (textController.text.length > 3) {
// code here
}else{
// some other code here
}
}
TextField code
TextField(
controller: textController,
onChanged: (val) {
streamController.add(val);
},
)

Answer 2

In my case I also required flutter async.
//pubspec.yaml
stream_transform: ^2.0.0
import 'dart:async';
import 'package:stream_transform/stream_transform.dart';
StreamController<String> streamController = StreamController();
// In init function
streamController.stream
.debounce(Duration(seconds: 1))
.listen((s) => {
// your code
});
// In build function
TextField(
style: TextStyle(fontSize: 16),
controller: messageController,
onChanged: (val) {
myMetaRef.child("isTyping").set(true);
streamController.add(val);
},
)

Answer 3

I find something so lighter in this link
it define this class
class Debouncer {
final int milliseconds;
Timer? _timer;
Debouncer({this.milliseconds=500});
run(VoidCallback action) {
if (null != _timer) {
_timer!.cancel();
}
_timer = Timer(Duration(milliseconds: milliseconds), action);
}
}
this sample will help you more
TextField(
decoration: new InputDecoration(hintText: 'Search'),
onChanged: (string) {
_debouncer.run(() {
print(string);
//perform search here
});
},
),