A package for managing ViewModel that depends on anlifecycle. Similar to Androidx ViewModel.

Usage

1.1 Prepare the lifecycle environment.

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    // Use LifecycleApp to wrap the default App
    return LifecycleApp(
      child: MaterialApp(
        title: 'ViewModel Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        navigatorObservers: [
          //Use LifecycleNavigatorObserver.hookMode() to register routing event changes
          LifecycleNavigatorObserver.hookMode(),
        ],
        home: const MyHomePage(title: 'ViewModel Home Page'),
      ),
    );
  }
}

The current usage of PageView and TabBarViewPageView should be replaced with LifecyclePageView and LifecycleTabBarView. Alternatively, you can wrap the items with LifecyclePageViewItem. You can refer to anlifecycle for guidance.

1.2 Use viewModels

class ViewModelHome with ViewModel {
  final ValueNotifier<int> counter = ValueNotifier<int>(0);

  ViewModelHome(Lifecycle lifecycle) {
    /// Associate the ValueNotifier with the Lifecycle, and automatically call dispose when the lifecycle ends.
    counter.bindLifecycle(lifecycle);
  }

  void incrementCounter() {
    counter.value++;
  }
}


class MyHomePage extends StatelessWidget {
  final String title;

  const MyHomePage({super.key, required this.title});

  @override
  Widget build(BuildContext context) {
    // Retrieve the ViewModel in the current environment.
    final ViewModelHome viewModel =
    context.viewModels(factory2: ViewModelHome.new);

    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            AnimatedBuilder(
              animation: viewModel.counter,
              builder: (_, __) =>
                  Text(
                    '${viewModel.counter.value}',
                    style: Theme
                        .of(context)
                        .textTheme
                        .headlineMedium,
                  ),
            ),
          ],
        ),
      ),
      floatingActionButton: const HomeFloatingButton(),
    );
  }
}

/// Simulate child widgets.
class HomeFloatingButton extends StatefulWidget {
  const HomeFloatingButton({super.key});

  @override
  State<HomeFloatingButton> createState() => _HomeFloatingButtonState();
}

class _HomeFloatingButtonState extends State<HomeFloatingButton> {
  //Retrieve the ViewModel in the current environment.
  late final vm = viewModelsOfState<ViewModelHome>();

  @override
  Widget build(BuildContext context) {
    return FloatingActionButton(
      onPressed: vm.incrementCounter,
      tooltip: 'Increment',
      child: const Icon(Icons.add),
    );
  }
}

Additional information

See anlifecycle

See cancelable

See an_lifecycle_cancellable