定期更新Angular2中的Observable值 [英] Periodically updating Observable value in Angular2

问题描述

我想从HTTP链接中每5秒钟打一次，而且似乎是使用angular2，一个可以观察到的是否可以走？

I'd like to hit and display every 5 seconds from a http link, and it seems to be that using angular2, an observable would be the way to go?

getPhaseVotes(issue: string) {
    return this.http.get(this.URL + 'issue/' + issue + '/getPhaseVotes')
        .subscribe(data => this.phase_votes = data.json(),
                   err => console.log(err),
                   () => this.getStatus(issue));
}

我应该如何每5秒更新一次？

How should I be updating this every 5 seconds?

推荐答案

您可以使用间隔运算符可观察

You could use the interval operator of Observable:

@Injeactable()
export class SomeService {
  constructor(private http:Http) {}

  getPhaseVotes(issue: string) {
    return Observable.interval(5000).flatMap(() => {
      return this.http.get(this.URL + 'issue/' + issue + '/getPhaseVotes')
        .map(res => res.json());
    });
  }
}

这样你需要调用一次 getPhaseVotes 方法并订阅。每5秒钟，HTTP请求将被透明地执行，并且在订阅的回调中提供结果：

This way you need to call once the getPhaseVotes method and subscribe on it. Every 5 seconds, an HTTP request will be executed transparently and the result provided within the subscribed callback:

@Component({
  (...)
})
export class SomeComponent {
  constructor(private service:SomeService) {
    this.service.getPhaseVotes('someissue')
      .subscribe(data => this.phase_votes = data,
               err => console.log(err),
               () => this.getStatus(issue));
  }
}

这篇文章可以给你更多的提示，其轮询部分：

This article could give you more hints in its "Polling" section:

• https://jaxenter.com/reactive-programming-http-and-angular-2-124560.html

• https://jaxenter.com/reactive-programming-http-and-angular-2-124560.html

这篇关于定期更新Angular2中的Observable值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！