Repeat HTTP call until the desired value is returned with RxJs-CodePudding

I need to repeat the query if the field of the returned object has the value 'INPROGRESS' with a delay so as not to clog up the server. If another field value is returned, the loop stops and I perform some action in subscribe() with its response.

My attempts so far have ended up with this code, where unfortunately the queries repeat infinitely.

this.service
.query(id: number)
.pipe(
  repeatWhen(obs => obs.pipe(delay(1000))),
  filter((response) => response.Status === 'INPROGRESS'),
  take(1),
)
.subscribe(...)

CodePudding user response：

with a recursie function, something like this should do the job:

private myFunc(){
    this.myRecursiveFunc(1).subscribe(response => console.log(response));
}


private myRecursiveFunc(id: number, response?:any):Observable<any>{
    if(response && response.Status !== 'INPROGRESS'){
        return of(response);
    }
    return this.service.query(id).pipe(
        delay(1000),
        concatMap(response => this.myRecursiveFunc(id, response)
    );
}

CodePudding user response：

rxjs has expand operator which will allow us to make recurive api call

Try this

 this.service
      .query(id: number)
      .pipe(
        delay(1000),
        expand((response: any) => {
          if (response.Status === 'INPROGRESS') {
            return return this.service
          .query(id: number).pipe(delay(1000));
          }
          return EMPTY;
        }),
        takeLast(1)
      )
      .subscribe(...)

CodePudding user response：

https://stackblitz.com/edit/rxjs-kafps9?file=index.ts

this.service.query(id: number).pipe(
  repeat({ delay: 1000 }),
  skipWhile((response) => response.Status === 'INPROGRESS'),
  take(1),
).subscribe(...)