Getting instance of service without constructor injection

Question

I have a @Injectable service defined in bootstrap. I want to get the instance of the service without using constructor injection. I tried using Reflective

Answer 1

Another approach would consist of defining a custom decorator (a CustomInjectable to set the metadata for dependency injection:

export function CustomComponent(annotation: any) {
  return function (target: Function) {

    // DI configuration
    var parentTarget = Object.getPrototypeOf(target.prototype).constructor;
    var parentAnnotations = Reflect.getMetadata('design:paramtypes', parentTarget);

    Reflect.defineMetadata('design:paramtypes', parentAnnotations, target);

    // Component annotations / metadata
    var annotations = Reflect.getOwnMetadata('annotations', target);
    annotations = annotations || [];
    annotations.push(annotation);
    Reflect.defineMetadata('annotations', annotations, target);
  }
}

It will leverage the metadata from the parent constructor instead of its own ones. You can use it on the child class:

@Injectable()
export class SomeService {
  constructor(protected http:Http) {
  }
}

@Component()
export class BaseComponent {
  constructor(private service:SomeService) {
  }
}

@CustomComponent({
  (...)
})
export class TestComponent extends BaseComponent {
  constructor() {
    super(arguments);
  }

  test() {
    console.log('http = '+this.http);
  }
}

See this question for more details:

• Angular2 use imported libs from base class