Lets say I have a API operation that consumes a List of CustomObjects. For every one of those objects it calls a service method that creates a Mono. How do I create a Flux from those Mono objects in an idiomatic and therefore non-blocking way?
What I've come up with for now is this. I changed the method names to better reflect their intended purpose.
fun myApiMethod(@RequestBody customObjs: List<CustomObject>): Flux<CustomObject> {
return Flux.create { sink ->
customObjs.forEach {
service.persistAndReturnMonoOfCustomObject(it).map {
sink.next(it)
}
}
sink.complete()
}
}
Moreover do I need to subscribe to the flux to actually make it return something?
I believe you can use concat() instead:
/**
* Concatenate all sources provided as a vararg, forwarding elements emitted by the
* sources downstream.
* <p>
* Concatenation is achieved by sequentially subscribing to the first source then
* waiting for it to complete before subscribing to the next, and so on until the
* last source completes. Any error interrupts the sequence immediately and is
* forwarded downstream.
* <p>
* <img class="marble" src="https://raw.githubusercontent.com/reactor/reactor-core/v3.1.3.RELEASE/src/docs/marble/concat.png" alt="">
* <p>
* @param sources The {@link Publisher} of {@link Publisher} to concat
* @param <T> The type of values in both source and output sequences
*
* @return a new {@link Flux} concatenating all source sequences
*/
@SafeVarargs
public static <T> Flux<T> concat(Publisher<? extends T>... sources) {
Or merge():
/**
* Merge data from {@link Publisher} sequences contained in an array / vararg
* into an interleaved merged sequence. Unlike {@link #concat(Publisher) concat},
* sources are subscribed to eagerly.
* <p>
* <img class="marble" src="https://raw.githubusercontent.com/reactor/reactor-core/v3.1.3.RELEASE/src/docs/marble/merge.png" alt="">
* <p>
* Note that merge is tailored to work with asynchronous sources or finite sources. When dealing with
* an infinite source that doesn't already publish on a dedicated Scheduler, you must isolate that source
* in its own Scheduler, as merge would otherwise attempt to drain it before subscribing to
* another source.
*
* @param sources the array of {@link Publisher} sources to merge
* @param <I> The source type of the data sequence
*
* @return a merged {@link Flux}
*/
@SafeVarargs
public static <I> Flux<I> merge(Publisher<? extends I>... sources) {