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IoC Container

Vania includes a lightweight inversion-of-control (IoC) container for dependency management. It supports factory registration and singleton resolution.

Registering Services​

Use IoCContainer to bind an interface or class to a factory function:

import 'package:vania/vania.dart';

// Register a factory (new instance each time)
IoCContainer().register<EmailService>(() => SmtpEmailService());

// Register a singleton (created once, reused)
IoCContainer().register<CacheService>(
  () => RedisCacheService(),
  singleton: true,
);

When singleton: true is set, the factory is called immediately and the instance is stored for all future resolutions.

Resolving Services​

var emailService = IoCContainer().resolve<EmailService>();
var cacheService = IoCContainer().resolve<CacheService>();

Each call to resolve() returns the singleton instance or calls the factory to create a new one, depending on how the service was registered.

Using in Service Providers​

The most common place to register services is inside a ServiceProvider:

class AppServiceProvider extends ServiceProvider {
  @override
  Future<void> register() async {
    IoCContainer().register<NotificationService>(
      () => PushNotificationService(env('FCM_KEY')),
      singleton: true,
    );

    IoCContainer().register<StorageService>(
      () => S3StorageService(
        bucket: env('AWS_BUCKET'),
        region: env('AWS_REGION'),
      ),
      singleton: true,
    );
  }

  @override
  Future<void> boot() async {}
}

Using in Controllers​

Resolve services in your controller methods:

class OrderController extends Controller {
  Future<Response> store(Request req) async {
    final notifier = IoCContainer().resolve<NotificationService>();
    // ... create order ...
    await notifier.send(userId, 'Order placed');
    return Response.json({'status': 'created'}, 201);
  }
}

Framework-Registered Services​

The framework registers a few services automatically:

  • RequestHandler — the HTTP request pipeline
  • SessionManager — session handling (singleton)

These are available via IoCContainer().resolve<T>() after application initialization.