inject_flutter 1.0.2

Flutter extension for inject.dart that simplifies ViewModel injection and lifecycle management to promote cleaner architecture in Flutter apps.

example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:inject_annotation/inject_annotation.dart';
import 'package:inject_flutter/inject_flutter.dart';

import 'main.inject.dart' as g;

void main() {
  final mainComponent = AppComponent.create();
  final app = mainComponent.exampleAppFactory.create();
  runApp(app);
}

/// The main component of the application.
/// Responsible for creating and managing dependencies of the application.
/// Root of the dependency graph.
@component
abstract class AppComponent {
  /// A factory method to create a new instance of [AppComponent].
  static const create = g.AppComponent$Component.create;

  /// Returns an instance of [ExampleAppFactory] to create the [ExampleApp] widget.
  @inject
  ExampleAppFactory get exampleAppFactory;
}

/// Factory to create the [ExampleApp] widget with the [HomePageFactory] injected.
@assistedFactory
abstract class ExampleAppFactory {
  ExampleApp create({Key? key});
}

/// The App.
class ExampleApp extends StatelessWidget {
  @assistedInject
  const ExampleApp({
    @assisted super.key,
    required this.homePageFactory,
  });

  /// The factory to create the [HomePage] widget.
  final HomePageFactory homePageFactory;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: homePageFactory.create(title: 'Flutter Demo Home Page'),
    );
  }
}

/// The ViewModel.
@inject
class HomePageViewModel extends ChangeNotifier {
  int count = 0;

  void init() {
    count = 5;
    notifyListeners();
  }

  void incrementCounter() {
    count++;
    notifyListeners();
  }
}

/// Factory to create the [HomePage] widget with the [MyHomePageFactory] injected.
/// [key] and [title] can be, but don't have to be provided at runtime.
@assistedFactory
abstract class HomePageFactory {
  HomePage create({
    Key? key,
    required String title,
  });
}

/// The HomePage.
class HomePage extends StatelessWidget {
  @assistedInject
  const HomePage({
    @assisted super.key,
    @assisted required this.title,
    required this.viewModelFactory,
  });

  final String title;

  /// Factory to create the [HomePageViewModel] which also handles the lifecycle of it
  /// and rebuilds the body when the [HomePageViewModel] gets updated.
  final ViewModelFactory<HomePageViewModel> viewModelFactory;

  @override
  Widget build(BuildContext context) {
    return viewModelFactory(
      init: (viewModel) {
        // simulate view model initialization
        // counter should start with 
        viewModel.init();
      },
      builder: (context, viewModel, _) {
        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:'),
                Text(
                  '${viewModel.count}',
                  style: Theme.of(context).textTheme.headlineMedium,
                ),
              ],
            ),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: viewModel.incrementCounter,
            child: const Icon(Icons.add),
          ),
        );
      },
    );
  }
}