flutter-setup-declarative-routing

# Implementing Routing and Deep Linking ## Contents - [Core Concepts](#core-concepts) - [Workflow: Initializing the Application and Router](#workflow-initializing-the-application-and-router) - [Workflow: Configuring Platform Deep Linking](#workflow-configuring-platform-deep-linking) - [Workflow: Implementing Nested Navigation](#workflow-implementing-nested-navigation) - [Examples](#examples) ## Core Concepts Use the `go_router` package for declarative routing in Flutter. It provides a robust API for complex routing scenarios, deep linking, and nested navigation. - **GoRouter**: The central configuration object defining the application's route tree. - **GoRoute**: A standard route mapping a URL path to a Flutter screen. - **ShellRoute / StatefulShellRoute**: Wraps child routes in a persistent UI shell (e.g., a `BottomNavigationBar`). `StatefulShellRoute` maintains the state of parallel navigation branches. - **Path URL Strategy**: Removes the default `#` fragment from web URLs, essential for clean deep linking across platforms. ## Workflow: Initializing the Application and Router Follow this workflow to bootstrap a new Flutter application with `go_router` and configure the root routing mechanism. ### Task Progress - [ ] Create the Flutter application. - [ ] Add the `go_router` dependency. - [ ] Configure the URL strategy for web/deep linking. - [ ] Implement the `GoRouter` configuration. - [ ] Bind the router to `MaterialApp.router`. ### 1. Scaffold the Application Run the following commands to create the app and add the required routing package: ```bash flutter create <app-name> cd <app-name> flutter pub add go_router ``` ### 2. Configure the Router Define a top-level `GoRouter` instance. Handle authentication or state-based routing using the `redirect` parameter. ```dart import 'package:flutter/material.dart'; import 'package:go_router/go_router.dart'; import 'package:flutter_web_plugins/url_strategy.dart'; void main() { // Use path URL strategy to remove the '#' from web URLs usePathUrlStrategy(); runApp(const MyApp()); } final GoRouter _router = GoRouter( initialLocation: '/', routes: [ GoRoute( path: '/', builder: (context, state) => const HomeScreen(), routes: [ GoRoute( path: 'details/:id', builder: (context, state) => DetailsScreen(id: state.pathParameters['id']!), ), ], ), ], errorBuilder: (context, state) => ErrorScreen(error: state.error), ); class MyApp extends StatelessWidget { const MyApp({super.key}); @override Widget build(BuildContext context) { return MaterialApp.router( routerConfig: _router, title: 'Routing App', ); } } ``` ## Workflow: Configuring Platform Deep Linking Configure the native platforms to intercept specific URLs and route them into the Flutter application. ### Task Progress - [ ] Determine target platforms (iOS, Android, or both). - [ ] Apply conditional configuration for Android (Manifest + Asset Links). - [ ] Apply conditional configuration for iOS (Plist + Entitlements + AASA). - [ ] Run validator -> review errors -> fix. ### If configuring for Android: 1. **Modify `AndroidManifest.xml`**: Add the intent filter inside the `<activity>` tag for `.MainActivity`. ```xml <intent-filter android:autoVerify="true"> <action android:name="android.intent.action.VIEW" /> <category android:name="android.intent.category.DEFAULT" /> <category android:name="android.intent.category.BROWSABLE" /> <data android:scheme="http" android:host="yourdomain.com" /> <data android:scheme="https" /> </intent-filter> ``` 2. **Host `assetlinks.json`**: Serve the following JSON at `https://yourdomain.com/.well-known/assetlinks.json`. ```json [{ "relation": ["delegate_permission/common.handle_all_urls"], "target": { "namespace": "android_app", "package_name": "com.yourcompany.yourapp", "sha256_cert_fingerprints": ["YOUR_SHA256_FINGERPRINT"] } }] ``` ### If configuring for iOS: 1. **Modify `Info.plist`**: Opt-in to Flutter's default deep link handler. *Note: If using a third-party deep linking plugin (e.g., `app_links`), set this to `NO` to prevent conflicts.* ```xml <key>FlutterDeepLinkingEnabled</key> <true/> ``` 2. **Modify `Runner.entitlements`**: Add the associated domain. ```xml <key>com.apple.developer.associated-domains</key> <array> <string>applinks:yourdomain.com</string> </array> ``` 3. **Host `apple-app-site-association`**: Serve the following JSON (without a `.json` extension) at `https://yourdomain.com/.well-known/apple-app-site-association`. ```json { "applinks": { "apps": [], "details": [{ "appIDs": ["TEAM_ID.com.yourcompany.yourapp"], "paths": ["*"], "components": [{"/": "/*"}] }] } } ``` ### Validation Loop Run validator -> review errors -> fix. - **Android**: Test using ADB. ```bash adb shell 'am start -a android.intent.action.VIEW -c android.intent.category.BROWSABLE -d "https://yourdomain.com/details/123"' com.yourcompany.yourapp ``` - **iOS**: Test using `xcrun` on a booted simulator. ```bash xcrun simctl openurl booted https://yourdomain.com/details/123 ``` ## Workflow: Implementing Nested Navigation Use `StatefulShellRoute` to implement persistent UI shells (like a bottom navigation bar) that maintain the state of their child routes. ### Task Progress - [ ] Define `StatefulShellRoute.indexedStack` in the `GoRouter` configuration. - [ ] Create `StatefulShellBranch` instances for each navigation tab. - [ ] Implement the shell widget using `StatefulNavigationShell`. ```dart final GoRouter _router = GoRouter( initialLocation: '/home', routes: [ StatefulShellRoute.indexedStack( builder: (context, state, navigationShell) { return ScaffoldWithNavBar(navigationShell: navigationShell); }, branches: [ StatefulShellBranch( routes: [ GoRoute( path: '/home', builder: (context, state) => const HomeScreen(), ), ], ), StatefulShellBranch( routes: [ GoRoute( path: '/settings', builder: (context, state) => const SettingsScreen(), ), ], ), ], ), ], ); ``` ## Examples ### High-Fidelity Shell Widget Implementation Implement the UI shell that consumes the `StatefulNavigationShell` to handle branch switching. ```dart class ScaffoldWithNavBar extends StatelessWidget { const ScaffoldWithNavBar({ required this.navigationShell, super.key, }); final StatefulNavigationShell navigationShell; void _goBranch(int index) { navigationShell.goBranch( index, // Support navigating to the initial location when tapping the active tab. initialLocation: index == navigationShell.currentIndex, ); } @override Widget build(BuildContext context) { return Scaffold( body: navigationShell, bottomNavigationBar: NavigationBar( selectedIndex: navigationShell.currentIndex, onDestinationSelected: _goBranch, destinations: const [ NavigationDestination(icon: Icon(Icons.home), label: 'Home'), NavigationDestination(icon: Icon(Icons.settings), label: 'Settings'), ], ), ); } } ``` ### Programmatic Navigation Use the `context.go()` and `context.push()` extension methods provided by `go_router`. ```dart // Replaces the current route stack with the target route (Declarative) context.go('/details/123'); // Pushes the target route onto the existing stack (Imperative) context.push('/details/123'); // Navigates using a named route and path parameters context.goNamed('details', pathParameters: {'id': '123'}); // Pops the current route context.pop(); ```