Webflux combine two Monos with dependency-CodePudding

I want to create a Spring-Webflux-Service that combines the data of two sources with a dependency. I'm new to Webflux so I have no idea how to do that. Here is some pseudo code to shows what I`m trying to do:

@Service
public class ServiceB {

    private RepositoryB repositoryB;
    private ServiceA serviceA;

    public Mono<BigDecimal> calculate(UUID id) {
        return repositoryB.findById(id)
                .flatMap(b -> serviceA.find(b.getId()))
                .flatMap((a, b) -> a   b);

    }

The result of repositoryB includes the identifier of the data I want to find with serviceA. At least I want to work on both datasets. What method could I use instead of the first flatMap?

CodePudding user response：

You may want to use Mono.zipWhen, to zip the two Monos into a Tuple:

public Mono<BigDecimal> calculate(UUID id) {
    return repositoryB.findById(id)
            .zipWhen(b -> serviceA.find(b.getId())
            .map(t -> t.getT1().add(t.getT2()));
}

Also, please note, you can not add two BigDecimals with .