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Optional Borje S Vintage Evening 50s Fashion Formal Multicolor Retro Swing Dresses XXL Cocktail Dresses Print Formal Evening Swing 50s Optional Vintage Print Dresses Borje XXL Dresses Cocktail Fashion S Multicolor Retro

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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();
    

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