go_router counter

main.dart

import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';

void main() {
  runApp(const MyApp());
}

/// The route configuration.
final GoRouter _router = GoRouter(
  routes: <RouteBase>[
    GoRoute(
      path: '/',
      name: 'counter',
      builder: (BuildContext context, GoRouterState state) {
        final parameter = state.uri.queryParameters['c'];
        final maybeCounter = parameter == null ? 0 : int.tryParse(parameter);
        final counter = maybeCounter ?? 0;
        return HomeScreen(counter: counter);
      },
    ),
  ],
);

class MyApp extends StatelessWidget {
  /// Constructs a [MyApp]
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routerConfig: _router,
    );
  }
}

class HomeScreen extends StatelessWidget {
  const HomeScreen({super.key, required this.counter});

  final int counter;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: MyHomePage(counter: counter),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key, required this.counter});

  final int counter;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Flutter Demo Home Page'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          context.goNamed('counter', queryParameters: {'c': '${counter + 1}'});
        },
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}