go-router（去路由器）

Go Router

GoRouter is a declarative routing package for Flutter that uses the Router API to provide convenient URL-based navigation.

Core Concepts

1. Router Configuration

Define routes as a list of GoRoute objects:

final GoRouter _router = GoRouter(
  initialLocation: '/',
  routes: [
    GoRoute(
      path: '/',
      builder: (context, state) => const HomeScreen(),
    ),
    GoRoute(
      path: '/user/:id',
      builder: (context, state) {
        final userId = state.pathParameters['id']!;
        return UserScreen(id: userId);
      },
    ),
  ],
);

2. Navigation

// Simple navigation
context.go('/details');

// With parameters
context.go('/user/123');

// Named navigation (requires name parameter)
context.goNamed('user', pathParameters: {'id': '123'});

// Push (adds to stack)
context.push('/modal');

// Replace current route
context.replace('/new');

// Go back
context.pop();

// With query parameters
context.go('/search?q=flutter');

3. Route Parameters

Path parameters use : prefix:

GoRoute(
  path: '/user/:id/posts/:postId',
  builder: (context, state) {
    final userId = state.pathParameters['id']!;
    final postId = state.pathParameters['postId']!;
    return PostScreen(userId: userId, postId: postId);
  },
)

Query parameters are accessed via state.uri.queryParameters:

GoRoute(
  path: '/search',
  builder: (context, state) {
    final query = state.uri.queryParameters['q'] ?? '';
    return SearchScreen(query: query);
  },
)

Common Patterns

Pattern 1: Authentication Guard with Redirection

final routerProvider = Provider<GoRouter>((ref) {
  final auth = ref.watch(authProvider);
  
  return GoRouter(
    initialLocation: '/',
    redirect: (context, state) {
      final isLoggedIn = auth.isLoggedIn;
      final isAuthRoute = state.matchedLocation == '/login';
      
      if (!isLoggedIn && !isAuthRoute) {
        return '/login';
      }
      if (isLoggedIn && isAuthRoute) {
        return '/';
      }
      return null;
    },
    routes: [
      GoRoute(path: '/login', builder: (_, __) => const LoginScreen()),
      GoRoute(path: '/', builder: (_, __) => const HomeScreen()),
    ],
  );
});

Pattern 2: ShellRoute for Bottom Navigation

GoRouter(
  routes: [
    ShellRoute(
      builder: (context, state, child) {
        return ScaffoldWithNavBar(child: child);
      },
      routes: [
        GoRoute(
          path: '/',
          builder: (_, __) => const HomeScreen(),
        ),
        GoRoute(
          path: '/settings',
          builder: (_, __) => const SettingsScreen(),
        ),
      ],
    ),
  ],
)

Pattern 3: StatefulShellRoute for Nested Navigation

StatefulShellRoute(
  branches: [
    StatefulShellBranch(
      routes: [GoRoute(path: '/feed', builder: (_, __) => FeedScreen())],
    ),
    StatefulShellBranch(
      routes: [GoRoute(path: '/profile', builder: (_, __) => ProfileScreen())],
    ),
  ],
)

Pattern 4: Custom Page Transitions

GoRoute(
  path: '/details',
  pageBuilder: (context, state) => const MaterialPage(
    child: DetailsScreen(),
  ),
  // Or custom transition
  pageBuilder: (context, state) => CustomTransitionPage(
    child: const DetailsScreen(),
    transitionsBuilder: (context, animation, secondaryAnimation, child) {
      return FadeTransition(
        opacity: CurveTween(curve: Curves.easeInOut).animate(animation),
        child: child,
      );
    },
  ),
)

Pattern 5: Error Handling

GoRouter(
  errorBuilder: (context, state) {
    return ErrorScreen(error: state.error);
  },
  // Or handle 404
  errorPageBuilder: (context, state) => MaterialPage(
    child: NotFoundScreen(path: state.uri.path),
  ),
)

Pattern 6: Type-Safe Routes (Go Router 14+)

Define typed routes:

part 'app_routes.g.dart';

@TypedGoRoute<HomeRoute>(path: '/')
class HomeRoute extends GoRouteData {
  @override
  Widget build(BuildContext context, GoRouterState state) {
    return const HomeScreen();
  }
}

@TypedGoRoute<UserRoute>(path: '/user/:id')
class UserRoute extends GoRouteData {
  final String id;
  const UserRoute({required this.id});
  
  @override
  Widget build(BuildContext context, GoRouterState state) {
    return UserScreen(id: id);
  }
}

Route State

Access route information in builders:

GoRoute(
  path: '/details',
  builder: (context, state) {
    // Path: state.uri.path
    // Query params: state.uri.queryParameters
    // Extra data: state.extra (passed via context.go('/details', extra: data))
    return DetailsScreen(
      path: state.uri.path,
      data: state.extra as MyData?,
    );
  },
)

Navigation Helper Methods

// Extension for cleaner navigation
extension NavigationHelpers on BuildContext {
  void goHome() => go('/');
  void goUser(String id) => go('/user/$id');
  void pushModal(Widget screen) => push('/modal', extra: screen);
}

// Usage
context.goHome();
context.goUser('123');

Web Support

Enable web URL handling:

GoRouter(
  // Handles browser back/forward
  // URL updates automatically
  initialLocation: '/',
  // For base href in web
  routerNeglect: true, // Disable browser history
)

// Access current route
final currentRoute = GoRouter.of(context).routeInformationProvider.value.uri.path;

Route Observers

GoRouter(
  observers: [RouteObserver()],
  navigatorBuilder: (context, state, child) {
    // Wrap all routes
    return SomeWrapper(child: child);
  },
)

Testing

testWidgets('navigates correctly', (tester) async {
  await tester.pumpWidget(
    MaterialApp.router(
      routerConfig: _router,
    ),
  );
  
  // Find and tap button
  await tester.tap(find.text('Go to details'));
  await tester.pumpAndSettle();
  
  // Verify navigation
  expect(find.text('Details'), findsOneWidget);
});

Code Generation

For type-safe routes with code generation:

dart run build_runner build

Generates:

• $route constant for route location
• Parameter classes for typed routes

Deep Linking

Configure Android & iOS for deep links, then handle in GoRouter:

GoRouter(
  routes: [
    GoRoute(
      path: '/product/:id',
      builder: (context, state) {
        // Handles myapp.com/product/123
        // and app://product/123
        return ProductScreen(id: state.pathParameters['id']!);
      },
    ),
  ],
)

Navigation Without Context

// Store router reference
final GoRouter router = GoRouter(...);

// Navigate without context
router.go('/home');
router.push('/modal');
router.pop();

See BEST_PRACTICES.md for architecture patterns.