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lib/13/go/others/extra_param.dart

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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';
+
+/// Family data class.
+class Family {
+  /// Create a family.
+  const Family({required this.name, required this.people});
+
+  /// The last name of the family.
+  final String name;
+
+  /// The people in the family.
+  final Map<String, Person> people;
+}
+
+/// Person data class.
+class Person {
+  /// Creates a person.
+  const Person({required this.name, required this.age});
+
+  /// The first name of the person.
+  final String name;
+
+  /// The age of the person.
+  final int age;
+}
+
+const Map<String, Family> _families = <String, Family>{
+  'f1': Family(
+    name: 'Doe',
+    people: <String, Person>{
+      'p1': Person(name: 'Jane', age: 23),
+      'p2': Person(name: 'John', age: 6),
+    },
+  ),
+  'f2': Family(
+    name: 'Wong',
+    people: <String, Person>{
+      'p1': Person(name: 'June', age: 51),
+      'p2': Person(name: 'Xin', age: 44),
+    },
+  ),
+};
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Extra Parameter';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        name: 'home',
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+        routes: <GoRoute>[
+          GoRoute(
+            name: 'family',
+            path: 'family',
+            builder: (BuildContext context, GoRouterState state) {
+              final Map<String, Object> params =
+                  state.extra! as Map<String, String>;
+              final String fid = params['fid']! as String;
+              return FamilyScreen(fid: fid);
+            },
+          ),
+        ],
+      ),
+    ],
+  );
+}
+
+/// The home screen that shows a list of families.
+class HomeScreen extends StatelessWidget {
+  /// Creates a [HomeScreen].
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: ListView(
+          children: <Widget>[
+            for (final MapEntry<String, Family> entry in _families.entries)
+              ListTile(
+                title: Text(entry.value.name),
+                onTap: () => context.goNamed('family',
+                    extra: <String, String>{'fid': entry.key}),
+              )
+          ],
+        ),
+      );
+}
+
+/// The screen that shows a list of persons in a family.
+class FamilyScreen extends StatelessWidget {
+  /// Creates a [FamilyScreen].
+  const FamilyScreen({required this.fid, super.key});
+
+  /// The family to display.
+  final String fid;
+
+  @override
+  Widget build(BuildContext context) {
+    final Map<String, Person> people = _families[fid]!.people;
+    return Scaffold(
+      appBar: AppBar(title: Text(_families[fid]!.name)),
+      body: ListView(
+        children: <Widget>[
+          for (final Person p in people.values)
+            ListTile(
+              title: Text(p.name),
+            ),
+        ],
+      ),
+    );
+  }
+}