Question

I have a web service that provide information about the (last) song that is currently playing on a radio.

How can my observable update the data from my http request by itself ?

My provider:

  load() : Observable<{}> {
    return this.http.get(this.URL).map(res => res.json());
  }

My component:

this.radio.load().subscribe(data => {
  console.log(data)
})

What I want, basically is "data" to be updated every time the web service response change ! How can i do that ?

Thank you very much

Answer 1

您可以执行以下操作：在您的组件中，每隔10秒调用load()，并检查数据是否已更改（我相信您要在组件上保存最多的属性最近的数据）。

以下是使用RxJS的方法：

IntervalObservable.create(10 * 1000 /* 10 seconds */)
    .takeWhile(() => this.alive) // only fires when component is alive
    .subscribe(() => {
        .radio.load()
        .subscribe(data => {
            /* ...check if data has changed... */
            console.log(data);
        });
});

关于this.alive - 这只是组件被销毁时（即调用ngOnDestroy时）需要设置为false的组件上的属性，并且需要设置为true时组件已初始化（可能在ngOnInit）。

（当然，您可以使用更传统的setInterval和clearInterval方式来做同样的事情。）

Check the change of api with observable and update data

1 个答案: