flutter drawer to remember the clicked item - flutter

Question

I want to remember the item that was clicked in drawer .
I am using the same widget for drawer ( sameDrawerOnly ) in all three widgets ( MyHomePage , FirstPage and SecondPage) and using variable itemClicked to trackthe item that was tapped inside setState . But the conditional formatting is not working.
Here is the code
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
DrawerOnly sameDrawerOnly = DrawerOnly();
class MyApp extends StatelessWidget {
final appTitle = 'Drawer Demo';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text(title)),
body: Center(child: Text('My Page!')),
drawer: sameDrawerOnly,
);
}
}
class DrawerOnly extends StatefulWidget {
const DrawerOnly ({
Key key,
}) : super(key: key);
#override
_DrawerOnlyState createState() => _DrawerOnlyState();
}
class _DrawerOnlyState extends State<DrawerOnly > {
int itemClicked = 0;
#override
Widget build(BuildContext ctxt) {
return Drawer(
child: new ListView(
children: <Widget>[
new DrawerHeader(
child: new Text("DRAWER HEADER.."),
decoration: new BoxDecoration(
color: Colors.orange
),
),
new ListTile(
title: new Text("Item => A", style: itemClicked==1 ? TextStyle( fontWeight: FontWeight.bold, color: Colors.red.withOpacity(0.6) ) : null),
onTap: () {
Navigator.pop(ctxt);
setState(() {
itemClicked=1;
});
Navigator.push(ctxt,
new MaterialPageRoute(builder: (ctxt) => new FirstPage()));
},
),
new ListTile(
title: new Text("Item => 2", style: itemClicked==2 ? TextStyle( fontWeight: FontWeight.bold , color: Colors.green.withOpacity(0.6) ) : TextStyle()),
onTap: () {
Navigator.pop(ctxt);
setState(() {
itemClicked=2;
});
Navigator.push(ctxt,
new MaterialPageRoute(builder: (ctxt) => new SecondPage()));
},
),
],
)
);
}
}
class FirstPage extends StatelessWidget {
#override
Widget build(BuildContext ctxt) {
return new Scaffold(
drawer: sameDrawerOnly,
appBar: new AppBar(title: new Text("First Page"),),
body: new Text("I belongs to First Page"),
);
}
}
class SecondPage extends StatelessWidget {
#override
Widget build(BuildContext ctxt) {
return new Scaffold(
drawer: sameDrawerOnly,
appBar: new AppBar(title: new Text("Second Page"),),
body: new Text("I belongs to Second Page"),
);
}
}

Answer 1

What went wrong
Although sameDrawerOnly was declared at the top most part of your file. Everytime the widget re-draws your app's screens, eg. opening FirstPage via MaterialPageRoute, the variable in the DrawerOnly widget will always stay to zero. Because it is always re-drawn based on your configuration.
What you can do
Hotfix: Make itemClicked a static variable. (Not Recommended)
// Before
int itemClicked
// After
static int itemClicked
Alternatively, you can refactor your code and use PageView instead of opening a new Scaffold widget every time you switch between drawer items. Then, you can now use currentPageValue to determine what item was selected by the user.
MyHomePage.dart
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
final appTitle = 'Drawer Demo';
#override
Widget build(BuildContext context) {
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatefulWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
#override
createState() => MyHomePageState();
}
class MyHomePageState extends State<MyHomePage> {
PageController _pageController;
double currentPageValue = 0.0;
#override
void initState() {
super.initState();
_pageController = PageController();
_pageController.addListener(() {
setState(() {
currentPageValue = _pageController.page;
// Do whatever you like with the page value
});
});
}
#override
void dispose() {
_pageController.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text(widget.title)),
body: Center(
child: PageView(
controller: _pageController,
children: <Widget>[
FirstPage(),
SecondPage(),
],
),
),
drawer: Drawer(
// Add a ListView to the drawer. This ensures the user can scroll
// through the options in the drawer if there isn't enough vertical
// space to fit everything.
child: ListView(
// Important: Remove any padding from the ListView.
padding: EdgeInsets.zero,
children: <Widget>[
DrawerHeader(
child: Text('Drawer Header'),
decoration: BoxDecoration(
color: Colors.blue,
),
),
ListTile(
title: Text('Item 1'),
onTap: () {
_pageController.jumpToPage(0);
Navigator.pop(context);
},
),
ListTile(
title: Text('Item 2'),
onTap: () {
_pageController.jumpToPage(1);
Navigator.pop(context);
},
),
],
),
),
);
}
}
class FirstPage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(color: Colors.red);
}
}
class SecondPage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(color: Colors.yellow);
}
}
View on dartpad.dev.
More on:
https://flutter.dev/docs/cookbook/design/drawer