Repeat Request based on data result

Question

Hi I'm new to angular and I want to know what is the right way of repeating GET request based on the resulting data.

item.service.ts

ScanItems():Observable<any>{
    return this.http.get<any>(url)     
}

item.component.ts

GetScannedItems(){
   this.ScanSubscription = this.itemService.ScanItems()
    .subscribe(
       data => {
         RDate = new Date(data.Date).getTime();
         const NDate = new Date().getTime();
         const Diff = RDate - NDate
         if(Diff > (-300000)){
           console.log('Valid')
         }
         else {
           // Repeat Request Here!!!
         }
       },
       error => console.error(error),
       () => this.ScanSubscription.unsubscribe()
   )
}

one option is to go traditional recursive call approach or another option is rxjs https://stackoverflow.com/questions/44981974/angular-correctly-using-rxjs-expand-operator-to-make-recursive-http-calls — Jameel Moideen, Oct 15 '18 at 03:48

Suresh Kumar Ariya · Accepted Answer · 2018-10-15T04:17:28.960

0

instead of handling in component, you can do this in service with retry operator.

GetScannedItems(){
   this.ScanSubscription = this.itemService.ScanItems()
    .pipe(
      map(
       data => {
         RDate = new Date(data.Date).getTime();
         const NDate = new Date().getTime();
         const Diff = RDate - NDate
         if(Diff > (-300000)){
           return of(true);
         }
         else {
            return Observable.throw('retry');
           // Repeat Request Here!!!
         }
       }),
       delay(500),
       retry()
   )
}

edited Oct 15 '18 at 04:17

answered Oct 15 '18 at 03:53

Suresh Kumar Ariya

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Don't make assumption.I think OP question is little bit different. He was asking a recursive approach. Retry will always send the same request again – Jameel Moideen Oct 15 '18 at 04:00
its a repeat request as per the title – Suresh Kumar Ariya Oct 15 '18 at 04:01
updated. check whether it works. or else we need to use flatMap – Suresh Kumar Ariya Oct 15 '18 at 04:17
thanks a lot, i've change `return Observable.throw()` to just `throw()` – Lowell Ed Llames Oct 15 '18 at 05:46

Repeat Request based on data result

1 Answers1