@Inject

Inject decorator is set of dependency injection system.

export declare let Inject: (
    value: string | Function, isMutable?: boolean
) => (Class: any, key?: string, paramIndex?: any) => any;

@Inject is used by injector in order to know where and what to inject at certain time. @Inject you can use in services, controllers, modules, route rules, filters.

Usage examples:

In services

@Injectable()
class ServiceA {

    @Inject(ServiceB)
    private myServ: ServiceB;
}

In controllers:

@Controller({
 name: 'home'
 providers: []
})
class Controller {

    // local to controller
    @Inject(ServiceB)
    private myServ: ServiceB;

    @Action('index')
    myCustomActionName( @Inject(ServiceC) myServ2: ServiceC ) {
       this.myServ.exec(); // access from local object
       myServ2.exec(); // access from local function scope;
    }
}

In modules:

@Module({
  name: 'myModule'
  imports: [ModuleB],
  providers: [ServiceB]
})
class MyNewModule implements IAfterConstruct {

    @Inject(ServiceB)
    private myServ: ServiceB;

    afterConstruct(): void {
        this.myServ.exec();
    }

}

In filters:

@Filter(20)
class BFilter implements IFilter {

  @Inject(ServiceB)
  private serviceB: ServiceB;

  before(data: string): string|Buffer|Promise<string|Buffer> {
    return "bFilter <- " + this.serviceB.transform(data);
  }

  after(data: string): string|Buffer|Promise<string|Buffer> {
    return "bFilter <- " + data;
  }

}