Angular2 Query Params Subscription Fires Twice

Question

Trying to handle an OAuth login scenario where if the user lands on a page with authorization_code in the query string, we process the token and continue

Answer 1

The best way to overcome this was subscribing router events, and processing query params only after the route is ticked to navigated state:

  public doSomethingWithQueryParams(): Observable {
      let observer: Observer;
      const observable = new Observable(obs => observer = obs);

      this.router.events.subscribe(evt => {
        // this is an injected Router instance
        if (this.router.navigated) {
          Observable.from(this.activatedRoute.queryParams)
            // some more processing here
            .subscribe(json => {
              observer.next(json);
              observer.complete();
            });
        }
      });
      return observable;
  }