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import 'package:flutter/material.dart'; | |
void main() { | |
runApp(NestedRouterDemo()); | |
} | |
class Book { | |
final String title; | |
final String author; | |
Book(this.title, this.author); | |
} | |
class NestedRouterDemo extends StatefulWidget { | |
@override | |
_NestedRouterDemoState createState() => _NestedRouterDemoState(); | |
} | |
class _NestedRouterDemoState extends State<NestedRouterDemo> { | |
BookRouterDelegate _routerDelegate = BookRouterDelegate(); | |
BookRouteInformationParser _routeInformationParser = | |
BookRouteInformationParser(); | |
@override | |
Widget build(BuildContext context) { | |
return MaterialApp.router( | |
title: 'Books App', | |
routerDelegate: _routerDelegate, | |
routeInformationParser: _routeInformationParser, | |
); | |
} | |
} | |
class BooksAppState extends ChangeNotifier { | |
int _selectedIndex; | |
Book _selectedBook; | |
final List<Book> books = [ | |
Book('Stranger in a Strange Land', 'Robert A. Heinlein'), | |
Book('Foundation', 'Isaac Asimov'), | |
Book('Fahrenheit 451', 'Ray Bradbury'), | |
]; | |
BooksAppState() : _selectedIndex = 0; | |
int get selectedIndex => _selectedIndex; | |
set selectedIndex(int idx) { | |
_selectedIndex = idx; | |
if (_selectedIndex == 1) { | |
// Remove this line if you want to keep the selected book when navigating | |
// between "settings" and "home" which book was selected when Settings is | |
// tapped. | |
selectedBook = null; | |
} | |
notifyListeners(); | |
} | |
Book get selectedBook => _selectedBook; | |
set selectedBook(Book book) { | |
_selectedBook = book; | |
notifyListeners(); | |
} | |
int getSelectedBookById() { | |
if (!books.contains(_selectedBook)) return 0; | |
return books.indexOf(_selectedBook); | |
} | |
void setSelectedBookById(int id) { | |
if (id < 0 || id > books.length - 1) { | |
return; | |
} | |
_selectedBook = books[id]; | |
notifyListeners(); | |
} | |
} | |
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> { | |
@override | |
Future<BookRoutePath> parseRouteInformation( | |
RouteInformation routeInformation) async { | |
final uri = Uri.parse(routeInformation.location); | |
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') { | |
return BooksSettingsPath(); | |
} else { | |
if (uri.pathSegments.length >= 2) { | |
if (uri.pathSegments[0] == 'book') { | |
return BooksDetailsPath(int.tryParse(uri.pathSegments[1])); | |
} | |
} | |
return BooksListPath(); | |
} | |
} | |
@override | |
RouteInformation restoreRouteInformation(BookRoutePath configuration) { | |
if (configuration is BooksListPath) { | |
return RouteInformation(location: '/home'); | |
} | |
if (configuration is BooksSettingsPath) { | |
return RouteInformation(location: '/settings'); | |
} | |
if (configuration is BooksDetailsPath) { | |
return RouteInformation(location: '/book/${configuration.id}'); | |
} | |
return null; | |
} | |
} | |
class BookRouterDelegate extends RouterDelegate<BookRoutePath> | |
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> { | |
final GlobalKey<NavigatorState> navigatorKey; | |
BooksAppState appState = BooksAppState(); | |
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() { | |
appState.addListener(notifyListeners); | |
} | |
BookRoutePath get currentConfiguration { | |
if (appState.selectedIndex == 1) { | |
return BooksSettingsPath(); | |
} else { | |
if (appState.selectedBook == null) { | |
return BooksListPath(); | |
} else { | |
return BooksDetailsPath(appState.getSelectedBookById()); | |
} | |
} | |
} | |
@override | |
Widget build(BuildContext context) { | |
return Navigator( | |
key: navigatorKey, | |
pages: [ | |
MaterialPage( | |
child: AppShell(appState: appState), | |
), | |
], | |
onPopPage: (route, result) { | |
if (!route.didPop(result)) { | |
return false; | |
} | |
if (appState.selectedBook != null) { | |
appState.selectedBook = null; | |
} | |
notifyListeners(); | |
return true; | |
}, | |
); | |
} | |
@override | |
Future<void> setNewRoutePath(BookRoutePath path) async { | |
if (path is BooksListPath) { | |
appState.selectedIndex = 0; | |
appState.selectedBook = null; | |
} else if (path is BooksSettingsPath) { | |
appState.selectedIndex = 1; | |
} else if (path is BooksDetailsPath) { | |
appState.setSelectedBookById(path.id); | |
} | |
} | |
} | |
// Routes | |
abstract class BookRoutePath {} | |
class BooksListPath extends BookRoutePath {} | |
class BooksSettingsPath extends BookRoutePath {} | |
class BooksDetailsPath extends BookRoutePath { | |
final int id; | |
BooksDetailsPath(this.id); | |
} | |
// Widget that contains the AdaptiveNavigationScaffold | |
class AppShell extends StatefulWidget { | |
final BooksAppState appState; | |
AppShell({ | |
@required this.appState, | |
}); | |
@override | |
_AppShellState createState() => _AppShellState(); | |
} | |
class _AppShellState extends State<AppShell> { | |
InnerRouterDelegate _routerDelegate; | |
ChildBackButtonDispatcher _backButtonDispatcher; | |
void initState() { | |
super.initState(); | |
_routerDelegate = InnerRouterDelegate(widget.appState); | |
} | |
@override | |
void didUpdateWidget(covariant AppShell oldWidget) { | |
super.didUpdateWidget(oldWidget); | |
_routerDelegate.appState = widget.appState; | |
} | |
@override | |
void didChangeDependencies() { | |
super.didChangeDependencies(); | |
// Defer back button dispatching to the child router | |
_backButtonDispatcher = Router.of(context) | |
.backButtonDispatcher | |
.createChildBackButtonDispatcher(); | |
} | |
@override | |
Widget build(BuildContext context) { | |
var appState = widget.appState; | |
// Claim priority, If there are parallel sub router, you will need | |
// to pick which one should take priority; | |
_backButtonDispatcher.takePriority(); | |
return Scaffold( | |
appBar: AppBar(), | |
body: Router( | |
routerDelegate: _routerDelegate, | |
backButtonDispatcher: _backButtonDispatcher, | |
), | |
bottomNavigationBar: BottomNavigationBar( | |
items: [ | |
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'), | |
BottomNavigationBarItem( | |
icon: Icon(Icons.settings), label: 'Settings'), | |
], | |
currentIndex: appState.selectedIndex, | |
onTap: (newIndex) { | |
appState.selectedIndex = newIndex; | |
}, | |
), | |
); | |
} | |
} | |
class InnerRouterDelegate extends RouterDelegate<BookRoutePath> | |
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> { | |
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>(); | |
BooksAppState get appState => _appState; | |
BooksAppState _appState; | |
set appState(BooksAppState value) { | |
if (value == _appState) { | |
return; | |
} | |
_appState = value; | |
notifyListeners(); | |
} | |
InnerRouterDelegate(this._appState); | |
@override | |
Widget build(BuildContext context) { | |
return Navigator( | |
key: navigatorKey, | |
pages: [ | |
if (appState.selectedIndex == 0) ...[ | |
FadeAnimationPage( | |
child: BooksListScreen( | |
books: appState.books, | |
onTapped: _handleBookTapped, | |
), | |
key: ValueKey('BooksListPage'), | |
), | |
if (appState.selectedBook != null) | |
MaterialPage( | |
key: ValueKey(appState.selectedBook), | |
child: BookDetailsScreen(book: appState.selectedBook), | |
), | |
] else | |
FadeAnimationPage( | |
child: SettingsScreen(), | |
key: ValueKey('SettingsPage'), | |
), | |
], | |
onPopPage: (route, result) { | |
appState.selectedBook = null; | |
notifyListeners(); | |
return route.didPop(result); | |
}, | |
); | |
} | |
@override | |
Future<void> setNewRoutePath(BookRoutePath path) async { | |
// This is not required for inner router delegate because it does not | |
// parse route | |
assert(false); | |
} | |
void _handleBookTapped(Book book) { | |
appState.selectedBook = book; | |
notifyListeners(); | |
} | |
} | |
class FadeAnimationPage extends Page { | |
final Widget child; | |
FadeAnimationPage({Key key, this.child}) : super(key: key); | |
Route createRoute(BuildContext context) { | |
return PageRouteBuilder( | |
settings: this, | |
pageBuilder: (context, animation, animation2) { | |
var curveTween = CurveTween(curve: Curves.easeIn); | |
return FadeTransition( | |
opacity: animation.drive(curveTween), | |
child: child, | |
); | |
}, | |
); | |
} | |
} | |
// Screens | |
class BooksListScreen extends StatelessWidget { | |
final List<Book> books; | |
final ValueChanged<Book> onTapped; | |
BooksListScreen({ | |
@required this.books, | |
@required this.onTapped, | |
}); | |
@override | |
Widget build(BuildContext context) { | |
return Scaffold( | |
body: ListView( | |
children: [ | |
for (var book in books) | |
ListTile( | |
title: Text(book.title), | |
subtitle: Text(book.author), | |
onTap: () => onTapped(book), | |
) | |
], | |
), | |
); | |
} | |
} | |
class BookDetailsScreen extends StatelessWidget { | |
final Book book; | |
BookDetailsScreen({ | |
@required this.book, | |
}); | |
@override | |
Widget build(BuildContext context) { | |
return Scaffold( | |
body: Padding( | |
padding: const EdgeInsets.all(8.0), | |
child: Column( | |
crossAxisAlignment: CrossAxisAlignment.start, | |
children: [ | |
FlatButton( | |
onPressed: () { | |
Navigator.of(context).pop(); | |
}, | |
child: Text('Back'), | |
), | |
if (book != null) ...[ | |
Text(book.title, style: Theme.of(context).textTheme.headline6), | |
Text(book.author, style: Theme.of(context).textTheme.subtitle1), | |
], | |
], | |
), | |
), | |
); | |
} | |
} | |
class SettingsScreen extends StatelessWidget { | |
@override | |
Widget build(BuildContext context) { | |
return Scaffold( | |
body: Center( | |
child: Text('Settings screen'), | |
), | |
); | |
} | |
} |
This example works! https://github.com/Mr-Pepe/nested-navigation/blob/master/lib/main.dart
You can navigate to subpages of a tab, and switch to another one, then back.
Taken from https://medium.com/@Mr_Pepe/nested-navigation-with-a-bottom-navigation-bar-using-flutter-d3c5086fbcdc
The state is not saved, eg if I select one of the books, then go to settings and back to books, I am back at the starting screen.
Please read the line 52-52 and uncomment the line 55. This should make it work as you expect
This example works! https://github.com/Mr-Pepe/nested-navigation/blob/master/lib/main.dart
You can navigate to subpages of a tab, and switch to another one, then back.
Taken from https://medium.com/@Mr_Pepe/nested-navigation-with-a-bottom-navigation-bar-using-flutter-d3c5086fbcdc
This is out of context because the gist here is about navigator 2.0 and this example you mentioned is navigator 1
In the end you can decide which way you want to go as both works : - )
Nice! Thanks @leonardarnold Indeed it works!
I will try this Nav 2 as I would eventually like Web and other builds, so trying to stick with official Flutter ....
PS I do notice this solution is 400 lines of code, while the nav 1 is 200. Hopefully, we can abstract away most of the stuff, and just plug in the paths eventually like good old html sites...
PS could we get an example where routes are not list items from a query, but perhaps predefined navigation steps, such as a checkout process.
Eg user confirms selection
user enters address
user payment
Essentially, it comes down to state management concepts, and the best solution still seems to be the BehaviorSubject solution described here https://fireship.io/lessons/flutter-state-management-guide/ therefore the entire navigation is essentially a stream.
The best!
I had an issue running this gist.
If url is on/settings
and manually set url to/book/1
, url would still stay at/settings
.Flutter (Channel dev, 1.23.0-7.0.pre, on Mac OS X 10.15.6 19G2021 x86_64, locale en-US) Engine revision 3a73d073c8 Dart version 2.11.0 (build 2.11.0-161.0.dev)
I have the same problem.
Re architecture, could we get sg like this instead of the super heavy logical labyrinth above? Lets keep it simple guys please
TabbedBarNav = [
Books(),
Coffees(),
];
Route Books = [
BookSettings();
BookSelect();
BookDetail;
];
Route Coffees = [
CoffeeSettings();
CoffeeSelect();
CoffeeDetail;
];
functionToSetSelectedTab () {
Mycustom-logic-to-decide-which-page-loads
}
@xwpony @giorgio79 you just need to update the selected index in setNewRoutePath
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
if (path is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (path is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (path is BooksDetailsPath) {
appState.selectedIndex = 0; // This was missing!
appState.setSelectedBookById(path.id);
}
}
}
I've just modify your code,the simple way
class BookRoutePath {
String url;
BookRoutePath(this.url);
}
so we don't need so many state for route,we could navgator like react router
all worked,but back button in detail screen couldn't.
can you tell me what wrong with me?
when we use back button in browser,it worked....
the whole code here:
import 'package:flutter/material.dart';
void main() {
runApp(NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
@OverRide
_NestedRouterDemoState createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State {
BookRouterDelegate _routerDelegate = BookRouterDelegate();
BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@OverRide
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
String _appUrl;
final List books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _appUrl = '/';
String get appUrl => _appUrl;
set appUrl(String idx) {
_appUrl = idx;
notifyListeners();
}
Book getBookById(int id) {
if (id < 0 || id > books.length - 1) {
return null;
}
return books[id];
}
int getIdByBook(Book book) {
if (!books.contains(book)) return 0;
return books.indexOf(book);
}
int getIdFromUrl(String path) {
final uri = Uri.parse(path);
return int.tryParse(uri.pathSegments[1]);
}
// Book get selectedBook => _selectedBook;
// set selectedBook(Book book) {
// _selectedBook = book;
// notifyListeners();
// }
// int getSelectedBookById(int id) {
// if (!books.contains(_selectedBook)) return 0;
// return books.indexOf(_selectedBook);
// }
// void setSelectedBookById(int id) {
// if (id < 0 || id > books.length - 1) {
// return;
// }
// _selectedBook = books[id];
// notifyListeners();
// }
}
class BookRouteInformationParser extends RouteInformationParser {
@OverRide
Future parseRouteInformation(
RouteInformation routeInformation) async {
//final uri = Uri.parse(routeInformation.location);
return (BookRoutePath(routeInformation.location));
}
@OverRide
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
//if (configuration.url == null) return null;
return RouteInformation(location: configuration.url);
}
}
class BookRouterDelegate extends RouterDelegate
with ChangeNotifier, PopNavigatorRouterDelegateMixin {
final GlobalKey navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey() {
appState.addListener(notifyListeners);
}
BookRoutePath get currentConfiguration {
return BookRoutePath(appState.appUrl);
}
@OverRide
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
//这里通过设定selectredBook,从而显示列表?
// if (appState.selectedBook != null) {
// appState.selectedBook = null;
// }
print('onPopPage,route.settings.name=${route.settings.name}');
appState.appUrl = route.settings.name;
notifyListeners();
return true;
},
);
}
@OverRide
Future setNewRoutePath(BookRoutePath path) async {
print('setNewRoutePath:path=${path.url}');
appState.appUrl = path.url; //这里来设定状态,但是我们已经notify了;
// if (path is BooksListPath) {
// appState.selectedIndex = 0;
// appState.selectedBook = null;
// } else if (path is BooksSettingsPath) {
// appState.selectedIndex = 1;
// } else if (path is BooksDetailsPath) {
// appState.setSelectedBookById(path.id);
// }
// }
}
}
// Routes
class BookRoutePath {
String url;
BookRoutePath(this.url);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
final BooksAppState appState;
AppShell({
@required this.appState,
});
@OverRide
_AppShellState createState() => _AppShellState();
}
class _AppShellState extends State {
InnerRouterDelegate _routerDelegate;
ChildBackButtonDispatcher _backButtonDispatcher;
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@OverRide
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@OverRide
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context)
.backButtonDispatcher
.createChildBackButtonDispatcher();
}
@OverRide
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
//_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
bottomNavigationBar: BottomNavigationBar(
items: [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(
icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: 0, //appState.selectedIndex,
onTap: (newIndex) {
appState.appUrl = newIndex == 0 ? '/' : '/settings';
//appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate
with ChangeNotifier, PopNavigatorRouterDelegateMixin {
final GlobalKey navigatorKey = GlobalKey();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
@OverRide
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.appUrl == '/')
MaterialPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: ValueKey(appState.appUrl),
name: appState.appUrl),
if (appState.appUrl.startsWith('/post'))
MaterialPage(
name: appState.appUrl,
key: ValueKey(appState.appUrl),
child: BookDetailsScreen(
book: appState
.getBookById(appState.getIdFromUrl(appState.appUrl))),
),
if (appState.appUrl == '/settings')
MaterialPage(
name: appState.appUrl,
child: SettingsScreen(),
key: ValueKey(appState.appUrl),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) return false;
//appState.selectedBook = null;
print('onPopPage,route.settings.name=${route.settings.name}');
appState.appUrl = route.settings.name;
//notifyListeners();
return true;
},
);
}
@OverRide
Future setNewRoutePath(BookRoutePath path) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.appUrl = '/post/${appState.getIdByBook(book)}';
//notifyListeners();
}
}
class FadeAnimationPage extends Page {
final Widget child;
FadeAnimationPage({Key key, this.child}) : super(key: key);
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
final List books;
final ValueChanged onTapped;
BooksListScreen({
@required this.books,
@required this.onTapped,
});
@OverRide
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
BookDetailsScreen({
@required this.book,
});
@OverRide
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Back'),
),
if (book != null) ...[
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
@OverRide
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text('Settings screen'),
),
);
}
}
It's a bit unclear to me, why a nested router is necessary here. Could you elaborate on this a bit? There's also the line where the dispatcher takes priority (_backButtonDispatcher.takePriority()
). How would a parallel sub router work in this case? Thanks
What is special about ValueChanged<Book>
? If I want to pass more than one argument to a function?
How do we navigate to a named route (from another file / screen)? I've read that it is navigatorKey.currentState.pushNamed('/settings');
but that throws an error about navigatorKey. I see in this example in MaterialApp
the navigatorKey
is not being set - is that the issue? If so, how do we get it from the router and set it?
I also tried to update the BookAppState selectedIndex (which DOES work from within the router classes, but not from other classes and widgets in other files / screens) with Provider.of<BooksAppState>(context, listen: false).setSelectedIndex(1);
but that doesn't rebuild the view to the new route.
Hi guys, I'm new to Flutter/Dart following this example I've tried to change the FlatButton pop to the AppBar in the parent route:
FROM:
class BookDetailsScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
children: [
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Back'),
),
],
}
TO the parent AppShell state
class _AppShellState extends State<AppShell> {
InnerRouterDelegate _routerDelegate;
ChildBackButtonDispatcher _backButtonDispatcher;
return Scaffold(
appBar: AppBar(
leading: appState.selectedBook != null
? IconButton(
icon: Icon(Icons.arrow_back),
onPressed: () => _routerDelegate.popRoute(),
)
: null,
)
It's working, but I'm not sure if it's the best practice to use _routerDelegate.popRoute()
@jonasjuni it's probably better to post this on stackoverflow. Please post the link here too after you've done that.
@jonasjuni it's probably better to post this on stackoverflow. Please post the link here too after you've done that.
Thanks mate! it is here https://stackoverflow.com/questions/65480003/flutter-navigator-v2-0-how-to-pop-a-child-nested-route
I have a question, if i open a page that on the root level navigator,how can i close the page by back button? I have the problem that when i open some page in inner navigator, then open a root navigator page, i can't close the root navigator page until inner navigator has no more route
I have a question to the example discussed above from Mr. Pepe https://github.com/Mr-Pepe/nested-navigation/blob/master/lib/main.dart
Is there a way to lazy load the navigator and their underlying pages, which are put on the IndexedStack?
I have a question that has been asked before, about the general Router 2.0: flutter/flutter#45938 (comment) . Specifically about this nested router example, how are we managing the states of these two routers? The solution explained here: flutter/flutter#45938 (comment) is great, but doesn't seem to work for this two-router solution? Am I missing something? Additionally, similarly to @lukemadera above, using Provider for BookAppState doesn't rebuild the route.
Why the inner Router
cannot be wired to parse route?
This would be much simpler if we could just do
MaterialApp(
home: Scaffold(
body: Router(
routerDelegate: _myRouterDelegate,
routeInformationParser: _myRouteInformationParser,
routeInformationProvider: PlatformRouteInformationProvider(
initialRouteInformation: RouteInformation(location: '/my-initial-route'),
),
backButtonDispatcher: RootBackButtonDispatcher(),
),
bottomNavigationBar: ...,
),
)
@jonasjuni I've a tweak for adding the back button on the AppBar based on this sample code. Please check it out.
- In the
_AppShellState
class, remove theappBar
property from its Scaffold
Widget build(BuildContext context) {
...
return Scaffold(
// <- Comment out this appBar
// appBar: AppBar(
// leading: appState.selectedBook != null
// ? IconButton(
// icon: Icon(Icons.arrow_back),
// onPressed: () => _routerDelegate.popRoute(),
// )
// : null,
// ),
...
// Keep the rest part the same
);
}
- Add the
appBar
into each screens'Scaffold
, like this
class BooksListScreen extends StatelessWidget {
...
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(), // <- This is the key
...
);
}
}
Hope this makes sense
Thanks @xmkevinchen !!!!
The state of the home list not get saved when scrolling down the list and switching to the settings page and navigate to home again, the list scroll offset gets reset.
Does anyone know how to fix this?
import 'package:flutter/material.dart';
void main() {
runApp(NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
@override
_NestedRouterDemoState createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
BookRouterDelegate _routerDelegate = BookRouterDelegate();
BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book _selectedBook;
final List<Book> books = [
Book('Book 1', 'Ray Bradbury'),
Book('Book 2', 'Ray Bradbury'),
Book('Book 3', 'Ray Bradbury'),
Book('Book 4', 'Ray Bradbury'),
Book('Book 5', 'Ray Bradbury'),
Book('Book 6', 'Ray Bradbury'),
Book('Book 7', 'Ray Bradbury'),
Book('Book 8', 'Ray Bradbury'),
Book('Book 9', 'Ray Bradbury'),
Book('Book 10', 'Ray Bradbury'),
Book('Book 11', 'Ray Bradbury'),
Book('Book 12', 'Ray Bradbury'),
Book('Book 13', 'Ray Bradbury'),
Book('Book 14', 'Ray Bradbury'),
Book('Book 15', 'Ray Bradbury'),
Book('Book 16', 'Ray Bradbury'),
Book('Book 17', 'Ray Bradbury'),
Book('Book 18', 'Ray Bradbury'),
Book('Book 19', 'Ray Bradbury'),
Book('Book 20', 'Ray Bradbury'),
Book('Book 21', 'Ray Bradbury'),
Book('Book 22', 'Ray Bradbury'),
Book('Book 23', 'Ray Bradbury'),
Book('Book 24', 'Ray Bradbury'),
Book('Book 25', 'Ray Bradbury'),
Book('Book 26', 'Ray Bradbury'),
Book('Book 27', 'Ray Bradbury'),
Book('Book 28', 'Ray Bradbury'),
Book('Book 29', 'Ray Bradbury'),
Book('Book 30', 'Ray Bradbury'),
Book('Book 31', 'Ray Bradbury'),
Book('Book 32', 'Ray Bradbury'),
Book('Book 33', 'Ray Bradbury'),
Book('Book 34', 'Ray Bradbury'),
Book('Book 35', 'Ray Bradbury'),
Book('Book 36', 'Ray Bradbury'),
Book('Book 37', 'Ray Bradbury'),
Book('Book 38', 'Ray Bradbury'),
Book('Book 39', 'Ray Bradbury'),
Book('Book 40', 'Ray Bradbury'),
Book('Book 41', 'Ray Bradbury'),
Book('Book 42', 'Ray Bradbury'),
Book('Book 43', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
if (_selectedIndex == 1) {
// Remove this line if you want to keep the selected book when navigating
// between "settings" and "home" which book was selected when Settings is
// tapped.
// selectedBook = null;
}
notifyListeners();
}
Book get selectedBook => _selectedBook;
set selectedBook(Book book) {
_selectedBook = book;
notifyListeners();
}
int getSelectedBookById() {
if (!books.contains(_selectedBook)) return 0;
return books.indexOf(_selectedBook);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(
RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location);
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1]));
}
}
return BooksListPath();
}
}
@override
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return null;
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
if (path is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (path is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (path is BooksDetailsPath) {
appState.setSelectedBookById(path.id);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
final BooksAppState appState;
AppShell({
@required this.appState,
});
@override
_AppShellState createState() => _AppShellState();
}
class _AppShellState extends State<AppShell> {
InnerRouterDelegate _routerDelegate;
ChildBackButtonDispatcher _backButtonDispatcher;
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context)
.backButtonDispatcher
.createChildBackButtonDispatcher();
}
@override
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
bottomNavigationBar: BottomNavigationBar(
items: [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(
icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
FadeAnimationPage listPage;
FadeAnimationPage getList() {
if (listPage == null)
listPage = FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: ValueKey('BooksListPage'),
);
return listPage;
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
getList(),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook),
),
] else
FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.selectedBook = book;
notifyListeners();
}
}
class FadeAnimationPage extends Page {
final Widget child;
FadeAnimationPage({Key key, this.child}) : super(key: key);
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
final List<Book> books;
final ValueChanged<Book> onTapped;
BooksListScreen({
@required this.books,
@required this.onTapped,
}));
@override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
BookDetailsScreen({
@required this.book,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Back'),
),
if (book != null) ...[
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text('Settings screen'),
),
);
}
}
Upgrade to flutter sdk >= 2.12
import 'package:flutter/material.dart';
void main() {
runApp(NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
@override
_NestedRouterDemoState createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
BookRouterDelegate _routerDelegate = BookRouterDelegate();
BookRouteInformationParser _routeInformationParser = BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book? _selectedBook;
final List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
notifyListeners();
}
Book? get selectedBook => _selectedBook;
set selectedBook(Book? book) {
_selectedBook = book;
notifyListeners();
}
int? getSelectedBookById() {
if (_selectedBook == null || !books.contains(_selectedBook)) return null;
return books.indexOf(_selectedBook!);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location ?? '');
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1]));
}
}
return BooksListPath();
}
}
@override
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return RouteInformation();
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
if (path is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (path is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (path is BooksDetailsPath && path.id != null) {
appState.setSelectedBookById(path.id!);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int? id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
final BooksAppState appState;
AppShell({
required this.appState,
});
@override
_AppShellState createState() => _AppShellState();
}
class _AppShellState extends State<AppShell> {
late InnerRouterDelegate _routerDelegate;
late ChildBackButtonDispatcher _backButtonDispatcher;
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context).backButtonDispatcher!.createChildBackButtonDispatcher();
}
@override
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
bottomNavigationBar: BottomNavigationBar(
items: [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: ValueKey('BooksListPage'),
),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook!),
),
] else
FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath path) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.selectedBook = book;
notifyListeners();
}
}
class FadeAnimationPage extends Page {
final Widget child;
FadeAnimationPage({required LocalKey key, required this.child}) : super(key: key);
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
final List<Book> books;
final ValueChanged<Book> onTapped;
BooksListScreen({
required this.books,
required this.onTapped,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
final Book book;
BookDetailsScreen({
required this.book,
});
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text('Back'),
),
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text('Settings screen'),
),
);
}
}
If you are retrieving a list of books from Firestore (or some API), how do you refresh a list of books listed on BooksListScreen
when coming back from BookDetailsScreen
? Let's say you add a new book on BookDetailsScreen
, then you probably want to show the new book added to the list of books when coming back to BooksListScreen
.
Upgrade to Flutter SDK >= 3.0.0
import 'package:flutter/material.dart';
void main() {
runApp(const NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
const NestedRouterDemo({Key? key}) : super(key: key);
@override
State<NestedRouterDemo> createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
final BookRouterDelegate _routerDelegate = BookRouterDelegate();
final BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book? _selectedBook;
final List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
notifyListeners();
}
Book? get selectedBook => _selectedBook;
set selectedBook(Book? book) {
_selectedBook = book;
notifyListeners();
}
int? getSelectedBookById() {
if (_selectedBook == null || !books.contains(_selectedBook)) return null;
return books.indexOf(_selectedBook!);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(
RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location ?? '');
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1]));
}
}
return BooksListPath();
}
}
@override
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return const RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return const RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return const RouteInformation();
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
@override
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
@override
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath configuration) async {
if (configuration is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (configuration is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (configuration is BooksDetailsPath && configuration.id != null) {
appState.setSelectedBookById(configuration.id!);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int? id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatefulWidget {
const AppShell({
Key? key,
required this.appState,
}) : super(key: key);
final BooksAppState appState;
@override
State<AppShell> createState() => _AppShellState();
}
class _AppShellState extends State<AppShell> {
late InnerRouterDelegate _routerDelegate;
late ChildBackButtonDispatcher _backButtonDispatcher;
@override
void initState() {
super.initState();
_routerDelegate = InnerRouterDelegate(widget.appState);
}
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
// Defer back button dispatching to the child router
_backButtonDispatcher = Router.of(context)
.backButtonDispatcher!
.createChildBackButtonDispatcher();
}
@override
Widget build(BuildContext context) {
var appState = widget.appState;
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
bottomNavigationBar: BottomNavigationBar(
items: const [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(
icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
@override
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState get appState => _appState;
BooksAppState _appState;
set appState(BooksAppState value) {
if (value == _appState) {
return;
}
_appState = value;
notifyListeners();
}
InnerRouterDelegate(this._appState);
@override
Widget build(BuildContext context) {
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: const ValueKey('BooksListPage'),
),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook!),
),
] else
const FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath configuration) async {
// This is not required for inner router delegate because it does not
// parse route
assert(false);
}
void _handleBookTapped(Book book) {
appState.selectedBook = book;
notifyListeners();
}
}
class FadeAnimationPage extends Page {
const FadeAnimationPage({required LocalKey key, required this.child})
: super(key: key);
final Widget child;
@override
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
const BooksListScreen({
Key? key,
required this.books,
required this.onTapped,
}) : super(key: key);
final List<Book> books;
final ValueChanged<Book> onTapped;
@override
Widget build(BuildContext context) {
return Scaffold(
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () => onTapped(book),
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
const BookDetailsScreen({Key? key, required this.book}) : super(key: key);
final Book book;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: const Text('Back'),
),
Text(book.title, style: Theme.of(context).textTheme.headline6),
Text(book.author, style: Theme.of(context).textTheme.subtitle1),
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
const SettingsScreen({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return const Scaffold(
body: Center(
child: Text('Settings screen'),
),
);
}
}
- Why calling
notifyListeners();
in
onPopPage: (route, result) {
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
notifyListeners();
return true;
},
?
If we change appState.selectedBook = null;
then listeners will be called by the appState.addListener(notifyListeners);
isn't they?
- Why do we do
_routerDelegate.appState = widget.appState
in:
@override
void didUpdateWidget(covariant AppShell oldWidget) {
super.didUpdateWidget(oldWidget);
_routerDelegate.appState = widget.appState;
}
?
isn't appState
passed to InnerRouterDelegate
by reference, and so all the changes in the internals are reflected there?
- Why we do
appState.selectedBook = null;
in:
onPopPage: (route, result) {
appState.selectedBook = null;
notifyListeners();
return route.didPop(result);
}
instead of calling _handleBookTapped(null)
that we already have?
- Why
AppShell
isStatefulWidget
since it doesn't hold any state and
_backButtonDispatcher = Router.of(context)
.backButtonDispatcher!
.createChildBackButtonDispatcher();
could be done in 'build` method?
Anyway - this seem to work exactly the same:
import 'package:flutter/material.dart';
void main() {
runApp(const NestedRouterDemo());
}
class Book {
final String title;
final String author;
Book(this.title, this.author);
}
class NestedRouterDemo extends StatefulWidget {
const NestedRouterDemo({Key? key}) : super(key: key);
@override
State<NestedRouterDemo> createState() => _NestedRouterDemoState();
}
class _NestedRouterDemoState extends State<NestedRouterDemo> {
final BookRouterDelegate _routerDelegate = BookRouterDelegate();
final BookRouteInformationParser _routeInformationParser =
BookRouteInformationParser();
@override
Widget build(BuildContext context) => MaterialApp.router(
title: 'Books App',
routerDelegate: _routerDelegate,
routeInformationParser: _routeInformationParser,
);
}
class BooksAppState extends ChangeNotifier {
int _selectedIndex;
Book? _selectedBook;
final List<Book> books = [
Book('Stranger in a Strange Land', 'Robert A. Heinlein'),
Book('Foundation', 'Isaac Asimov'),
Book('Fahrenheit 451', 'Ray Bradbury'),
];
BooksAppState() : _selectedIndex = 0;
int get selectedIndex => _selectedIndex;
set selectedIndex(int idx) {
_selectedIndex = idx;
notifyListeners();
}
Book? get selectedBook => _selectedBook;
set selectedBook(Book? book) {
_selectedBook = book;
notifyListeners();
}
int? getSelectedBookById() {
if (_selectedBook == null || !books.contains(_selectedBook)) {
return null;
}
return books.indexOf(_selectedBook!);
}
void setSelectedBookById(int id) {
if (id < 0 || id > books.length - 1) {
return;
}
_selectedBook = books[id];
notifyListeners();
}
}
class BookRouteInformationParser extends RouteInformationParser<BookRoutePath> {
@override
Future<BookRoutePath> parseRouteInformation(
RouteInformation routeInformation) async {
final uri = Uri.parse(routeInformation.location ?? '');
if (uri.pathSegments.isNotEmpty && uri.pathSegments.first == 'settings') {
return BooksSettingsPath();
} else {
if (uri.pathSegments.length >= 2) {
if (uri.pathSegments[0] == 'book') {
return BooksDetailsPath(int.tryParse(uri.pathSegments[1]));
}
}
return BooksListPath();
}
}
@override
RouteInformation restoreRouteInformation(BookRoutePath configuration) {
if (configuration is BooksListPath) {
return const RouteInformation(location: '/home');
}
if (configuration is BooksSettingsPath) {
return const RouteInformation(location: '/settings');
}
if (configuration is BooksDetailsPath) {
return RouteInformation(location: '/book/${configuration.id}');
}
return const RouteInformation();
}
}
class BookRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
@override
final GlobalKey<NavigatorState> navigatorKey;
BooksAppState appState = BooksAppState();
BookRouterDelegate() : navigatorKey = GlobalKey<NavigatorState>() {
appState.addListener(notifyListeners);
}
@override
BookRoutePath get currentConfiguration {
if (appState.selectedIndex == 1) {
return BooksSettingsPath();
} else {
if (appState.selectedBook == null) {
return BooksListPath();
} else {
return BooksDetailsPath(appState.getSelectedBookById());
}
}
}
@override
Widget build(BuildContext context) {
print('BookRouterDelegate#build');
return Navigator(
key: navigatorKey,
pages: [
MaterialPage(
child: AppShell(appState: appState),
),
],
onPopPage: (route, result) {
print('BookRouterDelegate#onPopPage');
if (!route.didPop(result)) {
return false;
}
if (appState.selectedBook != null) {
appState.selectedBook = null;
}
return true;
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath configuration) async {
if (configuration is BooksListPath) {
appState.selectedIndex = 0;
appState.selectedBook = null;
} else if (configuration is BooksSettingsPath) {
appState.selectedIndex = 1;
} else if (configuration is BooksDetailsPath && configuration.id != null) {
appState.setSelectedBookById(configuration.id!);
}
}
}
// Routes
abstract class BookRoutePath {}
class BooksListPath extends BookRoutePath {}
class BooksSettingsPath extends BookRoutePath {}
class BooksDetailsPath extends BookRoutePath {
final int? id;
BooksDetailsPath(this.id);
}
// Widget that contains the AdaptiveNavigationScaffold
class AppShell extends StatelessWidget {
AppShell({
Key? key,
required this.appState,
}) : _routerDelegate = InnerRouterDelegate(appState), super(key: key);
final BooksAppState appState;
final InnerRouterDelegate _routerDelegate;
@override
Widget build(BuildContext context) {
// Defer back button dispatching to the child router
final ChildBackButtonDispatcher _backButtonDispatcher = Router.of(context)
.backButtonDispatcher!
.createChildBackButtonDispatcher();
// Claim priority, If there are parallel sub router, you will need
// to pick which one should take priority;
_backButtonDispatcher.takePriority();
return Scaffold(
appBar: AppBar(),
body: SafeArea(
top: false,
child: Router(
routerDelegate: _routerDelegate,
backButtonDispatcher: _backButtonDispatcher,
),
),
bottomNavigationBar: BottomNavigationBar(
items: const [
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
BottomNavigationBarItem(
icon: Icon(Icons.settings), label: 'Settings'),
],
currentIndex: appState.selectedIndex,
onTap: (newIndex) {
appState.selectedIndex = newIndex;
},
),
);
}
}
class InnerRouterDelegate extends RouterDelegate<BookRoutePath>
with ChangeNotifier, PopNavigatorRouterDelegateMixin<BookRoutePath> {
@override
final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
BooksAppState appState;
InnerRouterDelegate(this.appState) {
//not really needed, since InnerRouterDelegate is rebuild anyway everytime when BookRouterDelegate is rebuild
//appState.addListener(notifyListeners);
}
@override
Widget build(BuildContext context) {
print('InnerRouterDelegate#build');
return Navigator(
key: navigatorKey,
pages: [
if (appState.selectedIndex == 0) ...[
FadeAnimationPage(
child: BooksListScreen(
books: appState.books,
onTapped: _handleBookTapped,
),
key: const ValueKey('BooksListPage'),
),
if (appState.selectedBook != null)
MaterialPage(
key: ValueKey(appState.selectedBook),
child: BookDetailsScreen(book: appState.selectedBook!),
),
] else
const FadeAnimationPage(
child: SettingsScreen(),
key: ValueKey('SettingsPage'),
),
],
onPopPage: (route, result) {
print('InnerRouterDelegate#onPopPage');
_handleBookTapped(null);
return route.didPop(result);
},
);
}
@override
Future<void> setNewRoutePath(BookRoutePath configuration) async {
// This is not required for inner router delegate because it does not parse route
assert(false);
}
void _handleBookTapped(Book? book) {
appState.selectedBook = book;
}
}
class FadeAnimationPage extends Page {
const FadeAnimationPage({required LocalKey key, required this.child})
: super(key: key);
final Widget child;
@override
Route createRoute(BuildContext context) {
return PageRouteBuilder(
settings: this,
pageBuilder: (context, animation, animation2) {
var curveTween = CurveTween(curve: Curves.easeIn);
return FadeTransition(
opacity: animation.drive(curveTween),
child: child,
);
},
);
}
}
// Screens
class BooksListScreen extends StatelessWidget {
const BooksListScreen({
Key? key,
required this.books,
required this.onTapped,
}) : super(key: key);
final List<Book> books;
final ValueChanged<Book> onTapped;
@override
Widget build(BuildContext context) {
return Scaffold(
// appBar: AppBar(),
body: ListView(
children: [
for (var book in books)
ListTile(
title: Text(book.title),
subtitle: Text(book.author),
onTap: () {
onTapped(book);
},
)
],
),
);
}
}
class BookDetailsScreen extends StatelessWidget {
const BookDetailsScreen({Key? key, required this.book}) : super(key: key);
final Book book;
@override
Widget build(BuildContext context) {
return Scaffold(
// appBar: AppBar(), //if we want the AppBar back button to appear
body: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
ElevatedButton(
onPressed: () {
Navigator.of(context).pop();
},
child: const Text('Back'),
),
Text(book.title, style: Theme.of(context).textTheme.titleLarge),
Text(book.author, style: Theme.of(context).textTheme.titleMedium),
],
),
),
);
}
}
class SettingsScreen extends StatelessWidget {
const SettingsScreen({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) => const Scaffold(
// appBar: AppBar(),
body: Center(
child: Text('Settings screen'),
),
);
}
try setting a path name to MaterialPage