How to convert a Mono<Map<String, Optional<String>>> to a Flux<Tuple<String, Optional<String>>>

Question

I'm using WebFlux with Reactor and creating a rest service that aggregates and transforms results from an internal service call using WebFlux webclient.

The client returns a Mono<Map<String, Optional<String>>> which I want to disassemble in a Flux with key, value elements so that I can combine it later on.

I was thinking of converting the client response of type

Mono<Map<String, Optional<String>>> to a

Flux<Tuple<String, String>>

I know you can convert a Mono<List<String>> to a Flux<String> using responseMono.flatMapMany(Flux::fromIterable)

but I couldn't find a way to handle Maps.

Answer 1

You can use mono.flatMapMany(map -> Flux.fromIterable(map.entrySet())) which will give you a Flux<Entry<String, Optional<String>>>.

If you explicitly want it to be a Tuple, not an Entry, then just do:

mono.flatMapMany(map -> Flux.fromIterable(map.entrySet()))
        .map(e -> Tuples.of(e.getKey(), e.getValue()));