Understanding Mono.when

Question

I'm new to Spring WebFlux and do not fully understand the Mono.when(). The following code does not work as expected:

List<Mono<Void>> results= ....;
 
String textVar = "my text";

processors.forEach(p -> {
    Mono<Object> restResponseMono = client.getSomething();
    results.add(restResponseMono.doOnNext(resp -> {
      textVar = textVar + resp.getText();
    }).then());
});


Mono.when(results).then(
  //here it would expect modification of 'textVar'
  Mono.just(textVar);
)

After calling the Mono.when(results).then(...) I would expect all my changes to be applied to the textVar because in the docu it is written:

[...Aggregate given publishers into a new Mono that will befulfilled when all of the given Publishers have completed....]

And the restResponseMono.then() should also wait until everything is completed. So I do not know exactly where is my lack of understanding.

Answer 1

Publishers in the when parameter,When subscribe automatically subscribes. The way it works is simply this.

            Flux<Integer> m1 = Flux.just(1,2).doOnNext(e -> System.out.println("M1 doOnNext: " + e));
            Mono<Integer> m2 = Mono.just(12).doOnSuccess(e -> System.out.println("M2 doOnSuccess: " + e));

            Mono<String> mono = Mono.when(m1,m2).then(Mono.just("STR")).doOnSuccess(e -> System.out.println("_________when doOnSuccess: " + e));
            mono.log().subscribe(System.out::println, Exception::new, () -> System.out.println("Completed2."));