http - Angular 2 : Rendering data from Observables

Question

跟随插值

{{ (__responseData | async)?.calculation | json }}

输出以下结构

[
    {
        "gross": 26.625834,
        "net": 20.425833,
        "tax": 6.2000003
    }
]

我怎样才能变得恶心？

{{ (__responseData | async)?.calculation[0].gross }}

不起作用，以下所有尝试也不起作用:

{{ (__responseData.calculation[0] | async)?.gross }}
{{ (__responseData.calculation.[0].gross  | async) }}

怎么了？

编辑:作为解决方法，我使用 flatmap (this.__responseData.flatMap((data: any) => data.calculation);) 但我想要一个优雅的解决方案，..

Answer 1

这是Alexander的答案(Angular2-Github-平台)

你可以使用 *ngFor="let calculation of calculations | async"

@Component({
  selector: 'my-app',
  providers: [HTTP_PROVIDERS],
  template: `
    <div *ngFor="let calculation of calculations | async">
      Gross: {{ calculation.gross }}<br>
      Net: {{ calculation.net }}
    </div>
  `,
  directives: [NgFor]
})
export class App {
  calculations: Observable<{gross:number; net:number}[]>;

  constructor(private _http: Http) {
    this.calculations = this._http.get("./data.json")
                            .map(res => res.json().calculation)
  }
}

http://plnkr.co/edit/3ze70dYycQxNyXA286mX?p=preview