Optional

decorator stable

npm Package	@angular/core
Module	import { Optional } from '@angular/core';
Source	core/src/di/metadata.ts

How To Use

@Injectable()
class Car {
  constructor(@Optional() public engine:Engine) {}
}

Description

For more details, see the "Dependency Injection Guide".

Example

class Engine {}

@Injectable()
class Car {
  constructor(@Optional() public engine: Engine) {}
}

const injector = ReflectiveInjector.resolveAndCreate([Car]);
expect(injector.get(Car).engine).toBeNull();