Self • Angular

Angular Team

In the following example, the dependency can be resolved by the local injector when instantiating the class itself, but not when instantiating a child.

class Dependency {}

        @Injectable()
        class NeedsDependency {
          constructor(@Self() public dependency: Dependency) {}
        }

        let inj = Injector.create({
          providers: [
            {provide: Dependency, deps: []},
            {provide: NeedsDependency, deps: [[new Self(), Dependency]]},
          ],
        });
        const nd = inj.get(NeedsDependency);

        expect(nd.dependency instanceof Dependency).toBe(true);

        const child = Injector.create({
          providers: [{provide: NeedsDependency, deps: [[new Self(), Dependency]]}],
          parent: inj,
        });
        expect(() => child.get(NeedsDependency)).toThrowError();