di

Installation

npm install @decorators/di --save

Example

Fully working example can be found in example folder.

API

• @Injectable() - Registers class as provider in the container

@Injectable()
class HttpService {}

• @Inject(injectable: Injectable) - A parameter decorator that marks parameter as dependency.

@Injectable()
class HttpService {
  constructor(@Inject(API_URL) apiUrl: string) {}
}

• @Optional() - A parameter decorator that marks parameter as optional dependency.

@Injectable()
class HttpService {
  constructor(@Optional() @Inject(API_URL) apiUrl: string) {}
}

• InjectionToken - Creates a token that can be used in DI as Provider.

const API_URL = new InjectionToken('API_URL');
...
@Injectable()
class HttpService {
  constructor(@Inject(API_URL) apiUrl: string) {}
}

• Container - Container interface
  • .setParent(container: Container) - set parent container
  • .provide(providers: Providers[]) - Registers an array of providers.
  • .get<T>(injectable: Injectable): Promise<T> - Retrieves a Promise with an instance of the injectable, throws:
    • MissingProviderError if dependency provider wasn't found
    • RecursiveProviderError in case of recursive dependency injection

const container = new Container();

container.provide([
  {
    provide: 'Message',
    async useFactory() {
      return delay('Async Provider');
    },
  },
  {
    provide: 'Hello World',
    useClass: Service,
  },
]);

Multi-support

It's possible to provide multiple things using one injection token via multi flag:

container.provide([
  {
    provide: GLOBAL_PIPE,
    useClass: ServerPipe,
    multi: true
  },
  {
    provide: GLOBAL_PIPE,
    useClass: ErrorPipe,
    multi: true
  },
]);