I played around with angular2 and got stuck after a while.
Using http.get
works fine for a single request, but I want to poll live-data every 4 seconds, after tinkering for quite a while and reading a lot of reactivex stuff i ended up with:
Observable.timer(0,4000)
.flatMap(
() => this._http.get(this._url)
.share()
.map(this.extractData)
.catch(this.handleError)
)
.share();
Is there a simple way to start a (4 second) interval after the http.get
-observable has emitted the result of the request? (Or will I end up in observable-hell?)
Timeline i want:
Time(s): 0 - - - - - 1 - - - - - 2 - - - - - 3 - - - - - 4 - - - - - 5 - - - - - 6
Action: Request - - Response - - - - - - - - - - - - - - - - - - - -Request-...
Wait: | wait for 4 seconds -------------------------> |
Update to RxJS 6
import { timer } from 'rxjs';
import { concatMap, map, expand, catchError } from 'rxjs/operators';
pollData$ = this._http.get(this._url)
.pipe(
map(this.extractData),
catchError(this.handleError)
);
pollData$.pipe(
expand(_ => timer(4000).pipe(concatMap(_ => pollData$)))
).subscribe();
I'm using RxJS 5 and I'm not sure what the RxJS 4 equivalent operators are. Anyway here is my RxJS 5 solution, hope it helps:
var pollData = this._http.get(this._url)
.map(this.extractData)
.catch(this.handleError);
pollData.expand(
() => Observable.timer(4000).concatMap(() => pollData)
).subscribe();
The expand operator will emit the data and recursively start a new Observable with each emission