Black Waist 123 Neck 3 Round Slimming High Sleeve Summer Lace SYGoodBUY Elegant Dress 4 Woman 6xHF7U
Dark Chiffon Women Summer Slit V Neck Dresses s Blue Beach Floral Print Cruiize V Summer Beach Slit Cruiize Women Floral s Dark Print Dresses Neck Blue Chiffon

Beach Floral s Chiffon Blue Neck Slit V Cruiize Dark Women Summer Dresses Print qzBBwE

A constructor parameter decorator that marks a dependency as optional.

See also

Description

The DI framework provides null if the dependency is not found. For example, the following code allows the possibility of a null result:

class Engine {} @ Injectable() class Car { constructor(@ Optional() public engine: Engine) {} } const injector = ReflectiveInjector.resolveAndCreate([Car]); expect(injector.get(Car).engine).toBeNull();
      
      class Engine {}

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

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

Options