angularangular-dependency-injection

How to pass a default value with @Optional in Angular 20?

In Angular 20, how can we inject an optional InjectionToken with a default value?

In Angular <20, I used to do it as follows:

constructor(@Optional@Inject(FOO) private foo = true){}
Solution

  • With DI using the inject function this is quite straightforward:

    export class MyComponent {
  config = inject(FOO, { optional: true }) ?? true;
}

    Note: thanks to JSON Derulo for their answer on GitHub.