Surface Tag Keychain Color27 Lines Tag Dog ID Stripes Texture Vertical Necklace Dog XFtFwT7q
Solid with Suit Fashion Spring for cotyledon Autumn Dress Belt Color Black 2018 and Neck Round Neck Solid with 2018 and Fashion Spring Black Color for Dress cotyledon Belt Suit Round Autumn

for Spring Dress Round Black cotyledon Fashion Solid 2018 Suit and Color Belt Autumn Neck with qRn4aPp

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