Flutter

Critical Patterns

Widget Structure (REQUIRED)

// ✅ ALWAYS: Prefer StatelessWidget when possible
class UserCard extends StatelessWidget {
  final User user;

  const UserCard({super.key, required this.user});

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        title: Text(user.name),
        subtitle: Text(user.email),
      ),
    );
  }
}

State Management (REQUIRED)

// ✅ Use Riverpod for state management
final userProvider = FutureProvider<User>((ref) async {
  return await api.getUser();
});

// In widget
Consumer(
  builder: (context, ref, child) {
    final userAsync = ref.watch(userProvider);
    return userAsync.when(
      data: (user) => Text(user.name),
      loading: () => CircularProgressIndicator(),
      error: (e, s) => Text('Error: $e'),
    );
  },
)

Null Safety (REQUIRED)

// ✅ ALWAYS: Use null safety properly
String? nullableName;
String nonNullName = nullableName ?? 'Default';

// Use late for lazy initialization
late final UserService userService;

Decision Tree

Need simple UI?            → StatelessWidget
Need local state?          → StatefulWidget
Need shared state?         → Provider/Riverpod
Need navigation?           → GoRouter
Need forms?                → Form + TextFormField

Commands

flutter create myapp
flutter run
flutter build apk
flutter build ios
flutter test
flutter analyze