angular httpclient return an Observable

Question

private getScmServiceMeta(serviceId: string): Observable<any> {
    let service = this.getServiceItem(serviceId);

    if (service) {
        return this.httpClient.get(serviceUri).map((res: Response) => {
                return _.get(res, 'data.serviceinfo');
            })
    } else {
        return Observable.throw('backend server error');
    }
}

public inquireScmData(serviceId: string, params: object, templateId: string): Observable<any> {
    return this.getScmServiceMeta(serviceId).map((serviceInfo: any) => {

        let uri = serviceInfo.routeTemplate;

        // How to return the _.get(res, 'data') as an Observable ???
        return this.httpClient.get(uri).map((res: Response) => {
            if (_.startsWith(_.get(res, 'status.code'), '200')) {
                return _.get(res, 'data');
            } else {
                throw ('status code error');
            }
        })
    })
}

as the above code, I need to return an observable when call the function 'inquireScmData', but inside the function, it need to call another function 'getScmServiceMeta' which is also asynchronous and return also an Observable, so how to return the '_.get(res, 'data')' as an Observable??? thanks

return Observable.of(_.get(res, 'data') )

Fan Cheung
– Fan Cheung

2017-09-29 06:51:55 +00:00
Commented Sep 29, 2017 at 6:51 — Fan Cheung
– Fan Cheung, Commented Sep 29, 2017 at 6:51

xtianjohns · Accepted Answer · 2017-09-29 15:31:41Z

1

rxjs gives you a static method on Observable to do this.

Observable.of( _.get(res, 'data') );

Though, you'll then have an Observable<Observable<Observable<any>>>. Is that what you are intending, or do you just want to chain "async" operations. If so, you should maybe leave your code as is, and use mergeMap.

public inquireScmData(serviceId: string, params: object, templateId: string): Observable<any> {
  return this.getScmServiceMeta(serviceId).mergMap((serviceInfo: any) => {

    let uri = serviceInfo.routeTemplate;

    return this.httpClient.get(uri).map((res: Response) => {
      if (_.startsWith(_.get(res, 'status.code'), '200')) {
        return _.get(res, 'data');
      } else {
        throw ('status code error');
      }
    })
  })
}

answered Sep 29, 2017 at 15:31

xtianjohns

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1 Comment

tlt Over a year ago

shouldn't he use switchMap in this case?

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