How to Maintain State of Drawer's Child Widget - flutter

Question

I have a stateful widget, Counter, with a button and a counter that keeps track of how many times the button was pressed. This widget is in the drawer. When I close and open the drawer again, the counter is reset. How do I make it so that the counter is not reset upon closing and opening the drawer?
Here is the code:
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
drawer: Drawer(
child: Counter(),
),
appBar: AppBar(),
body: Container(),
),
);
}
}
class Counter extends StatefulWidget {
const Counter({super.key});
#override
State<Counter> createState() => _CounterState();
}
class _CounterState extends State<Counter> {
int _count = 0;
#override
Widget build(BuildContext context) {
return Column(
children: [
Text(_count.toString()),
ElevatedButton(
onPressed: () {
setState(() {
_count = _count + 1;
});
},
child: Text('Increment Counter'),
)
],
);
}
}

Answer 1

To keep state of a variable within the Drawer(), the real solution would be to use a State Management library.
However, what you can do is create a global variable and pass it down the tree to Drawer():
import 'package:flutter/material.dart';
void main() {
runApp( MyApp());
}
class MyApp extends StatelessWidget {
var counter = 0;
MyApp({super.key});
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
drawer: Drawer(
child: Counter(counter: counter,),
),
appBar: AppBar(),
body: Container(),
),
);
}
}
class Counter extends StatefulWidget {
int counter;
Counter({required this.counter,super.key});
#override
State<Counter> createState() => _CounterState();
}
class _CounterState extends State<Counter> {
#override
Widget build(BuildContext context) {
return Column(
children: [
Text(widget.counter.toString()),
ElevatedButton(
onPressed: () {
setState(() {
widget.counter = widget.counter + 1;
});
},
child: Text('Increment Counter'),
)
],
);
}
}