Opaque token - AngularBuildUp/angular-microworkshops-authorization GitHub Wiki

You can also use a token to register an object into Angular's DI and also use that to resolve. This works extremely well for non-class dependencies. Angular DI doesn’t work for non-class dependencies, like the const HERO_DI_CONFIG.

export interface AppConfig {
  apiEndpoint: string;
  title: string;
}

export const HERO_DI_CONFIG: AppConfig = {
  apiEndpoint: 'api.heroes.com',
  title: 'Dependency Injection'
};

import { OpaqueToken } from "@angular/core";

export let APP_CONFIG = new OpaqueToken("app.config");

You register the token with the name passed in the constructor. This way Angular will know to resolve this. You register using the OpaqueToken

providers: [ { provide: APP_CONFIG,  useValue: HERO_DI_CONFIG } ]

Usage:

constructor(@Inject(APP_CONFIG) private  _config: AppConfig) { … }