How to return Flux<String> in ServerResponse in WebFlux

Question

I have a Jdbc Layer which is returning Flux. While returning the data, the fromPublisher method, it's accepting other Serializable classes, but the method is not accepting Flux.

Approach 1

public Mono<ServerResponse> getNames(final ServerRequest request) {
               Flux<String> strings = Flux.just("a", "b", "c"); 
        return ServerResponse.ok().contentType(APPLICATION_JSON)
                .body(fromPublisher(response), String.class);
    }

Above approach is returning abc combined as a Single String.

I tried this,

return ServerResponse.ok()
                .contentType(APPLICATION_JSON)
                .body(BodyInserters.fromValue(response), List.class);

I tried this aswell.

 Mono<List<String>> mono = response.collectList();
ServerResponse.ok()
                .contentType(APPLICATION_JSON)
                .body(fromPublisher(mono, String.class));

but this is also giving a Runtime error of

> body' should be an object, for reactive types use a variant specifying
> a publisher/producer and its related element type

Flux is a stream not a list, so if you want to return a stream just return the flux directly, or remove the ”fromPublisher”. If you want to return a list you do a collectList on the flux and place the resulting Mono straight into the body — Toerktumlare
– Toerktumlare, Commented Jan 6, 2022 at 11:25
Please dont say ”i tried that aswell” tried what? All i pointed out? I dont see all your trials i pointed out in the question above. Also, dont say ”its still giving me an error” what error? We cant help you if you dont show us what you do what you get. If you expect help then please put in some effort — Toerktumlare
– Toerktumlare, Commented Jan 6, 2022 at 13:21

Michael McFadyen · Accepted Answer · 2022-01-06 13:08:16Z

3

Below is an example of how to send back a Flux<String> in the body of a response

Flux<String> strings = Flux.just("a", "b", "c");
ServerResponse.ok().body(strings, String.class);

answered Jan 6, 2022 at 13:08

Michael McFadyen

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4 Comments

Shiva kumar Over a year ago

This is not returning as a list, Its returning abc as single string in the response body.

Michael McFadyen Over a year ago

you didn't ask to return it as a list in your question. You asked to return a Flux<String> and this is how you do it

Shiva kumar Over a year ago

Oh, Okay. I meant it as List of Strings. my Bad.

Ashika Umanga Umagiliya Over a year ago

did you find the correct method? I also want to return it like ["a","b","c']

Shiva kumar · Accepted Answer · 2022-01-07 04:23:26Z

3

This is working.

Mono<List<String>> strings = Flux.just("a", "b", "c").collectList();
 
return strings.flatMap(string -> ServerResponse.ok()
                        .contentType(APPLICATION_JSON)
                        .bodyValue(string));

answered Jan 7, 2022 at 4:23

Shiva kumar

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