如何转换List< Mono<>>到Mono< List< T>&gt ;? [英] How to convert List<Mono<T>> to Mono<List<T>>?

问题描述

我有一个返回 Mono< Output> 的方法:

interface Processor {
  Mono<Output> process(Input input);
}

我想为集合执行此 processor 方法:

And I want to execute this processor method for a collection:

List<Input> inputs = // get inputs
Processor processor = // get processor
List<Mono<Output>> outputs = inputs.stream().map(supplier::supply).collect(toList());

但我想获取的 Mono< List< List< Output>> 而不是 List< Mono< Output>> ，

我尝试了 reduce ，但是最终结果看起来很笨拙:

I tried reduce, but the final result looks very clumsy:

Mono<List<Output>> result = inputs.stream().map(processor::process)
    .reduce(Mono.just(new ArrayList<>()),
        (monoListOfOutput, monoOfOutput) ->
            monoListOfOutput.flatMap(list -> monoOfOutput.map(output -> {
              list.add(output);
              return list;
            })),
        (left, right) ->
            left.flatMap(leftList -> right.map(rightList -> {
              leftList.addAll(rightList);
              return leftList;
            })));

我可以用更少的代码来实现吗?

Can I achieve this with less code?

推荐答案

如果您不必出于任何原因创建流，则可以从输入中创建Flux，对其进行映射并收集列表

If you don't have to create stream for any reason, you could create Flux from your inputs, map it and collect list

Flux.fromIterable(inputs).flatMap(processor::process).collectList();

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