How to execute Angular 2 http call every timeInterval with Rxjs 'interval' operator?

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 ?

Meir · Accepted Answer · 2016-12-02 13:55:17Z

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> } }

I'am subscribing to the method in my component, thx for the note about the statfull function +1

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