I’m new to WebFlux/Reactor and having trouble wrapping my head around how to write this piece of code. Basically, I have a Flux which has a nested List foo and a Mono<Set> bar and I’d like to only return items in foo that are contained in bar.
// these two lines are representations of what the data looks like
Flux<CategoryModel> foo = { Permissions = [ "UserRole1"] } // List<String>
Mono<Set<String>> bar = [ "UserRole1", "UserRole2" ];
var filteredFoo = foo.filter(m -> m.getPermissions().stream().anyMatch(perm -> bar.block().contains(foo)));
The problem with the above block of code is the .block() on the contains() and I don’t want to block. Not sure how to change this to have non blocking but still check if bar contains the perm item.
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Answer
To answer the question directly – don’t use filter(), use filterWhen(), which filters based on a publisher rather than a set value:
foo.filterWhen(m -> bar.map(set -> m.getPermissions().stream().anyMatch(perm -> set.contains(foo))));
Note that your code as-written is a bit odd however and I’ve just translated it directly – but it doesn’t make much sense at the moment for a couple of reasons:
You’re streaming over the permissions but not actually using the permission in your
anyMatch()lambda at present – so currently your code could be simplified to:foo.filterWhen(m -> bar.map(set -> set.contains(foo)));
Even given the above, you’re checking if your set contains
foo, which is the flux itself, so there’s no reasonable situation in which that would ever be true.