flutter number textfield with right symbol - flutter

Question

i am trying to implement text field with showing symbol of height at the right of the text. for example when user enter any input the TextField must be like:
180 cm
as you see above cm should be appear whenever any text changed and shouldn't be removable.
i am trying to achieve it by using following library but could success. any suggestion?
https://pub.dev/packages/flutter_masked_text2
here is what I tried:
var heightController = MaskedTextController(
mask: '000 cm',
);

Answer 1

you can try this
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Postfix Text Controller',
theme: ThemeData(
primarySwatch: Colors.blue,
brightness: Brightness.dark,
),
home: const MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key}) : super(key: key);
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final TextEditingController _textController = TextEditingController();
final String _userPostfix = " cm";
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
centerTitle: true,
title: const Text("Postfix Text Controller"),
),
body: Center(
child: Padding(
padding: const EdgeInsets.all(15.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
TextFormField(
controller: _textController,
onChanged: (value) {
if (value == _userPostfix) {
_textController.text = "";
return;
}
value.endsWith(_userPostfix)
? _textController.text = value
: _textController.text = value + _userPostfix;
_textController.selection = TextSelection.fromPosition(
TextPosition(
offset: _textController.text.length -
_userPostfix.length));
},
decoration: const InputDecoration(
labelText: "Height",
border: OutlineInputBorder(),
),
),
],
),
),
),
);
}
}

Answer 2

You can try this
TextField(
controller: _textController,
keyboardType: TextInputType.number,
onChanged: (val) {
_textController.text =
val.replaceAll("c", "").replaceAll("m", "") + " cm";
_textController.selection = TextSelection.fromPosition(
TextPosition(
offset: _textController.text.length - 3));
},
),