Mutiny - Discarding Failures when Combining Results of Several Unis

Question

I'm using Mutiny to try to fetch data from several external sources. Each call produces a list of results, and I am currently combining these results into one list in a Uni as follows:

List<Uni<List<Result>>> unis = new ArrayList<>();
for (Source source : sources) {
    unis.add(source.getResults());
}

return Uni.combine().all().unis(unis).combinedWith(
        responses -> {
            List<Result> res = new ArrayList<>();
            for (List<Result> response : (List<List<Result>>) responses) {
                res.addAll(response);
            }
            return res;
        }
);

When one of these Unis fails, though, the entire final Uni fails.

I want to be able to get the combined list of results from all of the calls that do not fail, and just log failures or something, but I can't figure out how to do this from the Mutiny documentation. Any help would be much appreciated.

Answer 1

You should have an error-handling strategy for each Uni then, so the combination only sees succeeeding Uni .

See:

• https://quarkus.io/blog/mutiny-failure-handling/
• https://smallrye.io/smallrye-mutiny/2.0.0/tutorials/handling-failures/