在角6中获取不带@view child decorator的view子元素

我有一个自定义组件的装饰器:

export const MyDecorator = () => {
  return (constructor: Function) => {
    constructor.prototype['ngAfterViewInit'] = function() {
      // I need to get component's view child here
    };      
  };
};

我需要在decorator中获得一个view子元素。在组件中,我可以使用@viewchild decorator获取此元素:

@MyDecorator()
@Component({
  selector: "app-my-component",
  templateUrl: "./my-component.html"
})
export class MyPage {
  @ViewChild(Content) content: Content;
}

如何在mydecorator中获取content元素?