How do I convert this code reactive using reactor/Mono?

Question

I am changing a java app to use reactive programming to allow asyncronous and nonblocking flow but I'm having trouble understanding the concepts to achieve this. A stream of siteIds are used to invoke third party APIs and eventually the response is saved into some storage.

The code I have now is blocking and I would like to remove that...

generateReport() returns a Mono< BaseResponse > object

getReportAndSave() retrieves and manipulates the report and saves it, then should return boolean.

listResult = siteIds.parallel()
                    .map(siteId -> generateReport(authToken, requestParams, siteId))
                    .map(response -> response.block(Duration.ofMinutes(asyncCallTimeout)))
                    .map(resp -> getReportAndSave(authToken, resp.getRequestId()))
                    .collect(Collectors.toList());

So far I have this which should be able to do the same except I dont know how to get a return value for listResult.

siteId.forEach(siteId -> generateReport(authToken, requestParams, siteId)
                            .subscribe(baseResponse -> getReportAndSave(authToken, baseResponse.getRequestId())));

listResult is a List of Booleans, saying if each siteId has successfully been saved into a blob storage.

Answer 1

final Flux<ResultWrapperBean> resultFlux = Flux.fromIterable(siteIds)
        // Since generateReport() returns Mono, here you should use flatMap instead of map.
        .flatMap(siteId -> generateReport(authToken, requestParams, siteId))
        // Use a wrapper bean to save the request id and request result.
        .map(resp -> new ResultWrapperBean(resp.getRequestId(), getReportAndSave(authToken, resp.getRequestId())));
resultFlux.subscribe(resultBean -> log.info("RequestId: {}, and request result is {}", resultBean.getRequestId(), resultBean.getResult()));