Spring reactor webclient sequential requests with flatmap and takewhile

Question

I want to retrieve all pages from a third-party resource. To do that I wrote this:

final WebClient webClient = WebClient.builder()
     .baseUrl("http://resource.com")
     .build();
Flux.fromStream(IntStream.iterate(0, i -> i + 1).boxed())
     .flatMap(i -> webClient.get()
          .uri("/data?page={page}", i)
          .retrieve()
          .bodyToMono(Page.class))
     .takeWhile(Page::isMoreAvailable)
     .flatMapIterable(Page::getData)

but it doesn't work properly. flatMap is called multiple times and it performs multiple requests with different pages before takeWhile retrieves the first response.

If I change it to this:

.map(i -> webClient.get()
        .uri("/data?page={page}", i)
        .retrieve()
        .bodyToMono(Page.class)
        .block())

it works well.

So, how can I achieve this with a flatMap?

score 1 · Accepted Answer · answered Feb 09 '18 at 10:49

1

ok, so flatmap processing concurrent

.flatMap(i -> webClient.get()
   .uri("/data?page={page}", i)
   .retrieve()
   .bodyToMono(Page.class), 1)

did the trick.

answered Feb 09 '18 at 10:49

Slava

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3
9

Can you tell please why the second parameter to `bodyToMono` did the trick? – Stav Alfi Feb 11 '18 at 21:46
@StavAlfi the second parameter is to `flatMap` – Slava Feb 12 '18 at 17:54

Spring reactor webclient sequential requests with flatmap and takewhile

1 Answers1