Configures the Injector to return a value of another useExisting token.

interface ExistingProvider extends ExistingSansProvider {
  provide: any
  multi?: boolean

  // inherited from core/ExistingSansProvider
  useExisting: any
}

See also

• "Dependency Injection Guide".

Properties

Usage notes

class Greeting {
  salutation = 'Hello';
}

class FormalGreeting extends Greeting {
  override salutation = 'Greetings';
}

const injector = Injector.create({
  providers: [
    {provide: FormalGreeting, deps: []}, {provide: Greeting, useExisting: FormalGreeting}
  ]
});

expect(injector.get(Greeting).salutation).toEqual('Greetings');
expect(injector.get(FormalGreeting).salutation).toEqual('Greetings');
expect(injector.get(FormalGreeting)).toBe(injector.get(Greeting));

Multi-value example

const locale = new InjectionToken<string[]>('locale');
const injector = Injector.create({
  providers: [
    {provide: locale, multi: true, useValue: 'en'},
    {provide: locale, multi: true, useValue: 'sk'},
  ]
});

const locales: string[] = injector.get(locale);
expect(locales).toEqual(['en', 'sk']);