context_di 0.2.0-Preview

context_di: ^0.2.0-Preview copied to clipboard

Project is based on Provider package. Main goal is to create a tool that will help reduce boilerplate code and make it easier to work with dependency injection via Provider.

Features #

2 scopes are supported:

• factory scope (creates instance every time)
• singleton scope (one instance per feature)

Parameterized factories

final bloc = context.resolveWithParams<Bloc>((id: _id));

Scopes based on widget tree lifecycle: [dispose.gif]

Added Code Generation #

add build_runner and [context_di_generator] to your project

dev_dependencies:
  build_runner:
  context_di_generator:

create empty feature class that extends FeatureDependencies with _$

part 'basic.feature.dart';

typedef EntityBlocParams = ({int id});

void _dispose(BuildContext context, Repository instance) => instance.dispose();

@Feature()
@Singleton(Repository, as: RepositoryInterface, dispose: _dispose)
@Factory(ListBloc)
@Factory(EntityBloc, params: EntityBlocParams)
class Basic extends FeatureDependencies with _$BasicFeatureMixin {
  const Basic({super.key, super.builder});
}

then run dart run build_runner build -d to generate feature file

Getting started #

Create a feature class that extends FeatureDependencies and override register method. When you need to register a dependency, use registerSingleton, registerSingletonAs, registerFactory or registerParamsFactory methods.

typedef EntityBlocParams = ({int id});

class BasicFeature extends FeatureDependencies {
  const BasicFeature({super.key, super.builder});

  @override
  List<Registration> register(BuildContext context) {
    return [
      registerSingletonAs<Repository, RepositoryInterface>(
        (context) => Repository(context.resolve()),
        dispose: (context, instance) => instance.dispose(),
      ),
      registerFactory(
        (context) => ListBloc(context.resolve<RepositoryInterface>()),
      ),
      registerParamsFactory(
        (context, EntityBlocParams params) => EntityBloc(
          params.id,
          context.resolve(),
        ),
      ),
    ];
  }
}

Add to your widget tree

@RoutePage()
class BasicFeaturePage extends StatelessWidget {
  const BasicFeaturePage({super.key});

  @override
  Widget build(BuildContext context) {
    return BasicFeature(builder: (context) {
      return _Content();
    });
  }
}

And resolve dependencies in feature co

class _Content extends StatefulWidget {
  const _Content();

  @override
  State<_Content> createState() => _ContentState();
}

class _ContentState extends State<_Content> {
  late final ListBloc _listBloc;

  int? _selectedId;

  @override
  void initState() {
    _listBloc = context.resolve<ListBloc>();
    super.initState();
  }

  @override
  void dispose() {
    _listBloc.close();
    super.dispose();
  }

  //...
}

@RoutePage()
class EntityPage extends StatelessWidget {
  final int _id;

  const EntityPage({super.key, required int id}) : _id = id;

  @override
  Widget build(BuildContext context) {
    return BlocProvider<EntityBloc>(
      create: (_) => context.resolveWithParams((id: _id)),
      child: BlocBuilder<EntityBloc, EntityState>(builder: (context, state) {
        return Scaffold(
          body: switch (state) {
            Initial() => Center(child: CircularProgressIndicator.adaptive()),
            Loaded() => _Content(state),
          },
        );
      }),
    );
  }
}

basic resolve

 final listBloc = context.resolve<ListBloc>();

parametrized resolve

 var create = (_) => context.resolveWithParams((id: _id));

Additional information #

IMPORTANT NOTICE! You can use resolve or resolveWithParams only in feature context, in lover levels of widget tree. If you have some core dependencies register them on app level:

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

  final _router = AppRouter();

  @override
  Widget build(BuildContext context) {
    return _RootDependencies(
      builder: (context) => MaterialApp.router(
        title: 'Flutter Demo',
        theme: ThemeData(
          colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
          useMaterial3: true,
        ),
        routerConfig: _router.config(),
      ),
    );
  }
}

class _RootDependencies extends FeatureDependencies {
  const _RootDependencies({super.builder});

  @override
  List<Registration> register(BuildContext context) {
    return [
      registerSingleton<Logger>((_) => Logger()),
    ];
  }
}