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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
final GlobalKey<NavigatorState> _rootNavigatorKey =
GlobalKey<NavigatorState>(debugLabel: 'root');
final GlobalKey<NavigatorState> _sectionANavigatorKey =
GlobalKey<NavigatorState>(debugLabel: 'sectionANav');
// This example demonstrates how to setup nested navigation using a
// BottomNavigationBar, where each bar item uses its own persistent navigator,
// i.e. navigation state is maintained separately for each item. This setup also
// enables deep linking into nested pages.
void main() {
runApp(NestedTabNavigationExampleApp());
}
/// An example demonstrating how to use nested navigators
class NestedTabNavigationExampleApp extends StatelessWidget {
/// Creates a NestedTabNavigationExampleApp
NestedTabNavigationExampleApp({super.key});
final GoRouter _router = GoRouter(
navigatorKey: _rootNavigatorKey,
initialLocation: '/a',
routes: <RouteBase>[
StatefulShellRoute.indexedStack(
builder: (BuildContext context, GoRouterState state,
StatefulNavigationShell navigationShell) {
// Return the widget that implements the custom shell (in this case
// using a BottomNavigationBar). The StatefulNavigationShell is passed
// to be able access the state of the shell and to navigate to other
// branches in a stateful way.
return ScaffoldWithNavBar(navigationShell: navigationShell);
},
branches: <StatefulShellBranch>[
// The route branch for the first tab of the bottom navigation bar.
StatefulShellBranch(
navigatorKey: _sectionANavigatorKey,
routes: <RouteBase>[
GoRoute(
// The screen to display as the root in the first tab of the
// bottom navigation bar.
path: '/a',
builder: (BuildContext context, GoRouterState state) =>
const RootScreen(label: 'A', detailsPath: '/a/details'),
routes: <RouteBase>[
// The details screen to display stacked on navigator of the
// first tab. This will cover screen A but not the application
// shell (bottom navigation bar).
GoRoute(
path: 'details',
builder: (BuildContext context, GoRouterState state) =>
const DetailsScreen(label: 'A'),
),
],
),
],
),
// The route branch for the second tab of the bottom navigation bar.
StatefulShellBranch(
// It's not necessary to provide a navigatorKey if it isn't also
// needed elsewhere. If not provided, a default key will be used.
routes: <RouteBase>[
GoRoute(
// The screen to display as the root in the second tab of the
// bottom navigation bar.
path: '/b',
builder: (BuildContext context, GoRouterState state) =>
const RootScreen(
label: 'B',
detailsPath: '/b/details/1',
secondDetailsPath: '/b/details/2',
),
routes: <RouteBase>[
GoRoute(
path: 'details/:param',
builder: (BuildContext context, GoRouterState state) =>
DetailsScreen(
label: 'B',
param: state.pathParameters['param'],
),
),
],
),
],
),
// The route branch for the third tab of the bottom navigation bar.
StatefulShellBranch(
routes: <RouteBase>[
GoRoute(
// The screen to display as the root in the third tab of the
// bottom navigation bar.
path: '/c',
builder: (BuildContext context, GoRouterState state) =>
const RootScreen(
label: 'C',
detailsPath: '/c/details',
),
routes: <RouteBase>[
GoRoute(
path: 'details',
builder: (BuildContext context, GoRouterState state) =>
DetailsScreen(
label: 'C',
extra: state.extra,
),
),
],
),
],
),
],
),
],
);
@override
Widget build(BuildContext context) {
return MaterialApp.router(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
routerConfig: _router,
);
}
}
/// Builds the "shell" for the app by building a Scaffold with a
/// BottomNavigationBar, where [child] is placed in the body of the Scaffold.
class ScaffoldWithNavBar extends StatelessWidget {
/// Constructs an [ScaffoldWithNavBar].
const ScaffoldWithNavBar({
required this.navigationShell,
Key? key,
}) : super(key: key ?? const ValueKey<String>('ScaffoldWithNavBar'));
/// The navigation shell and container for the branch Navigators.
final StatefulNavigationShell navigationShell;
@override
Widget build(BuildContext context) {
return Scaffold(
body: navigationShell,
bottomNavigationBar: BottomNavigationBar(
// Here, the items of BottomNavigationBar are hard coded. In a real
// world scenario, the items would most likely be generated from the
// branches of the shell route, which can be fetched using
// `navigationShell.route.branches`.
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Section A'),
BottomNavigationBarItem(icon: Icon(Icons.work), label: 'Section B'),
BottomNavigationBarItem(icon: Icon(Icons.tab), label: 'Section C'),
],
currentIndex: navigationShell.currentIndex,
onTap: (int index) => _onTap(context, index),
),
);
}
/// Navigate to the current location of the branch at the provided index when
/// tapping an item in the BottomNavigationBar.
void _onTap(BuildContext context, int index) {
// When navigating to a new branch, it's recommended to use the goBranch
// method, as doing so makes sure the last navigation state of the
// Navigator for the branch is restored.
navigationShell.goBranch(
index,
// A common pattern when using bottom navigation bars is to support
// navigating to the initial location when tapping the item that is
// already active. This example demonstrates how to support this behavior,
// using the initialLocation parameter of goBranch.
initialLocation: index == navigationShell.currentIndex,
);
}
}
/// Widget for the root/initial pages in the bottom navigation bar.
class RootScreen extends StatelessWidget {
/// Creates a RootScreen
const RootScreen({
required this.label,
required this.detailsPath,
this.secondDetailsPath,
super.key,
});
/// The label
final String label;
/// The path to the detail page
final String detailsPath;
/// The path to another detail page
final String? secondDetailsPath;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Root of section $label'),
),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text('Screen $label',
style: Theme.of(context).textTheme.titleLarge),
const Padding(padding: EdgeInsets.all(4)),
TextButton(
onPressed: () {
GoRouter.of(context).go(detailsPath, extra: '$label-XYZ');
},
child: const Text('View details'),
),
const Padding(padding: EdgeInsets.all(4)),
if (secondDetailsPath != null)
TextButton(
onPressed: () {
GoRouter.of(context).go(secondDetailsPath!);
},
child: const Text('View more details'),
),
],
),
),
);
}
}
/// The details screen for either the A or B screen.
class DetailsScreen extends StatefulWidget {
/// Constructs a [DetailsScreen].
const DetailsScreen({
required this.label,
this.param,
this.extra,
this.withScaffold = true,
super.key,
});
/// The label to display in the center of the screen.
final String label;
/// Optional param
final String? param;
/// Optional extra object
final Object? extra;
/// Wrap in scaffold
final bool withScaffold;
@override
State<StatefulWidget> createState() => DetailsScreenState();
}
/// The state for DetailsScreen
class DetailsScreenState extends State<DetailsScreen> {
int _counter = 0;
@override
Widget build(BuildContext context) {
if (widget.withScaffold) {
return Scaffold(
appBar: AppBar(
title: Text('Details Screen - ${widget.label}'),
),
body: _build(context),
);
} else {
return Container(
color: Theme.of(context).scaffoldBackgroundColor,
child: _build(context),
);
}
}
Widget _build(BuildContext context) {
return Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text('Details for ${widget.label} - Counter: $_counter',
style: Theme.of(context).textTheme.titleLarge),
const Padding(padding: EdgeInsets.all(4)),
TextButton(
onPressed: () {
setState(() {
_counter++;
});
},
child: const Text('Increment counter'),
),
const Padding(padding: EdgeInsets.all(8)),
if (widget.param != null)
Text('Parameter: ${widget.param!}',
style: Theme.of(context).textTheme.titleMedium),
const Padding(padding: EdgeInsets.all(8)),
if (widget.extra != null)
Text('Extra: ${widget.extra!}',
style: Theme.of(context).textTheme.titleMedium),
if (!widget.withScaffold) ...<Widget>[
const Padding(padding: EdgeInsets.all(16)),
TextButton(
onPressed: () {
GoRouter.of(context).pop();
},
child: const Text('< Back',
style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18)),
),
]
],
),
);
}
}