Flutter initState called every time I re-enter a page - flutter

Question

I have three pages, A, B, C, and I navigate between them through a Drawer.
My goal is to get initState to be called only once (when the page is inserted in the widget tree), so that the state of each page is not reinitialized when I return to it.
My fist try was to use Navigator.of(context).PushNamed(routeName) as shown in the code below.
Probably this doesn't work because if from A I call B and then A again, the navigator stack is
[A] --> [B, A] --> [A, B, A] and not
[A] -> [B, A] --> [A]
so a navigation based on pop() should be more appropriate. I tried with
onTap: () {
Navigator.of(context).canPop()
? Navigator.of(context)
.popUntil(ModalRoute.withName(PageA.routeName))
: Navigator.of(context).pushNamed(PageA.routeName);
},
instead of onTap: () => Navigator.of(context).pushNamed(PageA.routeName)
But it doesn't work: when I tap on a drawer item a black screen appears, without any exception or warning, as if the navigator called a blank screen...
What am I doing wrong? Any idea how to fix?
This is my code:
main.dart
import 'package:flutter/material.dart';
import 'page_c.dart';
import 'page_a.dart';
import 'page_b.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Navigation test',
home: PageA(),
routes: {
PageA.routeName: (ctx) => PageA(),
PageB.routeName: (ctx) => PageB(),
PageC.routeName: (ctx) => PageC(),
},
);
}
}
my_drawer.dart
import 'package:flutter/material.dart';
import 'page_b.dart';
import 'page_c.dart';
import 'page_a.dart';
class MyDrawer extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Drawer(
child: Column(
children: [
SizedBox(
height: 100,
),
ListTile(
title: Text('PAGE A'),
onTap: () => Navigator.of(context).pushNamed(PageA.routeName)),
ListTile(
title: Text('PAGE B'),
onTap: () => Navigator.of(context).pushNamed(PageB.routeName)),
ListTile(
title: Text('PAGE C'),
onTap: () => Navigator.of(context).pushNamed(PageC.routeName)),
],
),
);
}
}
page_a.dart
import 'package:flutter/material.dart';
import 'my_drawer.dart';
class PageA extends StatefulWidget {
static const routeName = '/route-a';
#override
_PageAState createState() => _PageAState();
}
class _PageAState extends State<PageA> {
#override
void initState() {
print('PAGE A INIT STATE');
super.initState();
}
// void didChangeDependencies() {
// print('PAGE A DID CHANGE DEPENDECIES');
// super.didChangeDependencies();
// }
// #override
// void dispose() {
// print('PAGE A DISPOSE');
// super.dispose();
// }
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('PAGE A')),
drawer: MyDrawer(),
body: Center(
child: Text('A', style: TextStyle(fontSize: 100)),
),
);
}
}
page_b.dart
import 'package:flutter/material.dart';
import 'my_drawer.dart';
class PageB extends StatefulWidget {
static const routeName = '/route-b';
#override
_PageBState createState() => _PageBState();
}
class _PageBState extends State<PageB> {
#override
void initState() {
print('PAGE B INIT STATE');
super.initState();
}
// void didChangeDependencies() {
// print('PAGE B DID CHANGE DEPENDECIES');
// super.didChangeDependencies();
// }
// #override
// void dispose() {
// print('PAGE B DISPOSE');
// super.dispose();
// }
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('PAGE B')),
drawer: MyDrawer(),
body: Center(
child: Text('B', style: TextStyle(fontSize: 100)),
),
);
}
}
page_c.dart
import 'package:flutter/material.dart';
import 'my_drawer.dart';
class PageC extends StatefulWidget {
static const routeName = '/route-c';
#override
_PageCState createState() => _PageCState();
}
class _PageCState extends State<PageC> {
#override
void initState() {
print('PAGE C INIT STATE');
super.initState();
}
// void didChangeDependencies() {
// print('PAGE C DID CHANGE DEPENDECIES');
// super.didChangeDependencies();
// }
// #override
// void dispose() {
// print('PAGE C DISPOSE');
// super.dispose();
// }
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('PAGE C')),
drawer: MyDrawer(),
body: Center(
child: Text('C', style: TextStyle(fontSize: 100)),
),
);
}
}