Pass variable name as a function parameter - flutter

Question

I want to pass a variable name as a function parameter, but it doesn't seem to work : the content of my variable remains unchanged.
Widget Field(String changedValue, String label, bool isTextObscured) {
return TextFormField(
decoration: InputDecoration(labelText: label),
validator: checkFieldEmpty,
onChanged: (value) {
setState(() {
changedValue = value;
});
},
obscureText: isTextObscured,
);
}
Here, I want to change the value of the variable who has the name "changedValue". When I do it directly with the variable name, it works, but when I try to use the parameter, nothing happens. Here's an example of where I used it :
Widget LoginFields() {
return Column(
children: [
Field(email, Strings.emailLabel, false),
Field(password, Strings.passwordLabel, true),
ValidationButton(),
],
);
}
Thanks in advance!

Answer 1

There are many things to clarify here, like:
setState() is a method, that must be called inside a StatefullWidget.
if you create a function, name it with lowerCamelCase (effective dart).
for returning a Widget prefer extend a Widget, especially if you need a State.
if you seek a guide for TextField in Flutter - check cookbook here and here.
Here how you can set it up:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Material App',
home: Scaffold(
appBar: AppBar(
title: Text('Material App Bar'),
),
body: Center(
child: Column(
children: [
FieldWidget(changedValueInitial: 'email', label: 'labelConstOne'),
FieldWidget(changedValueInitial: 'password', label: 'labelConstTwo', isTextObscured: true),
// ValidationButton(),
],
),
),
),
);
}
}
class FieldWidget extends StatefulWidget {
String changedValueInitial;
String label;
bool isTextObscured;
FieldWidget({
Key? key,
required this.changedValueInitial,
required this.label,
this.isTextObscured = false,
}) : super(key: key);
#override
_FieldWidgetState createState() => _FieldWidgetState();
}
class _FieldWidgetState extends State<FieldWidget> {
late String _changedValue;
#override
void initState() {
super.initState();
_changedValue = widget.changedValueInitial;
}
#override
Widget build(BuildContext context) {
return TextFormField(
decoration: InputDecoration(labelText: widget.label),
// validator: yourValidator,
initialValue: _changedValue,
onChanged: (value) {
setState(() {
_changedValue = value;
});
},
obscureText: widget.isTextObscured,
);
}
}
If that is what you need..