如何使用Rxjs'interval'运算符在每次timeInterval中执行Angular 2 http调用？

Question

I have this simple method in my service :

 notify(userID: string) {
    let _URL = this.baseUrl + '/notification/GetUnseen?userId=' + userID;
     this.datatService.set(_URL);
    return this.datatService.get()
        .flatMap((response) =>
           response.json().slice())
           .distinct();
}

It return a stream of object which contain informations about user's notification. i would like to execute this call every 5 second with interval operator without using setTimeout ?

When i try this :

 notify(userID: string) {
    let _URL = this.baseUrl + '/notification/GetUnseen?userId=' + userID;
     this.datatService.set(_URL);
    return this.datatService.get()
        **.interval(5000)**
        .flatMap((response) =>
           response.json().slice())
           .distinct();
}

I have an error. Any Suggestion ?

Answer 1

notify(userID: string) {
  return Observable.interval(5000)
    .map(() => this.baseUrl + '/notification/GetUnseen?userId=' + userID)
    .switchMap(url => {
      this.dataService.set(url);
      return this.dataService.get();
    })
    .map(response => ....{ <your handler> }
}

A few notes: 1. You must subscribe to the returned value to start the calls. 2. Your data service is statefull, this might create race condition where 2 different clients set the url and then invoke it, consider converting the get to a stateless function: get(url) , in which case your code will be

notify(userID: string) {
  return Observable.interval(5000)
    .map(() => this.baseUrl + '/notification/GetUnseen?userId=' + userID)
    .switchMap(url => this.dataService.get(url))
    .map(response => ....{ <your handler> }
}