RxJS将可观察到的内容追加到打字稿中的可观察到的数组列表中 [英] RxJS append observable to observable array list in typescript

问题描述

如何将Observable<News>添加到可观察数组?

How to add Observable<News> to an array of observable ?

newsArray: Observable<Array<any>>;

addNews(newsId: number) {
   let news = this.newsService.getNewNews(newsId); // this returns a Observable<News> type.

  //I want to add `news` to `newsArray` to display it in UI.
}

HTML:

<li *ngFor="let item of (newsArray | async)">
  <div>{{item.Id}}: {{item.DataValue}}</div>
</li>

还有其他运算符要使用吗?

Any other operators to use?

我尝试了BehaviourSubject，但是一次只显示一个值.我要显示要添加到错误中的添加项目.

I tried BehaviourSubject but it displays only one value at a time. I want to display add items that I am appending to an arrray.

推荐答案

您可以使用扫描来积累新闻

You can use scan to accumulate news

news$:Observable<any>
loadMore$=new Subject<number>()

ngOnInit(){
 this.news$=this.loadMore$
 .switchMap((newsId)=>this.newsService.getNewNews(newsId))
 .scan((acc,curr)=>{
    acc.push(curr)
    return acc
 },[]).startWith(null)
}

addNews(newsId: number) {
  this.loadMore$.next(newsId);
}

HTML

<li *ngFor="let item of (news$ | async)">
  <div>{{item.Id}}: {{item.DataValue}}</div>
</li>

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