Spring ServerResponseResultHandler can NOT handle "Mono<ServerResponse>"

Affects: \ 5.3.8

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org.springframework.web.reactive.function.server.support.ServerResponseResultHandler.java can NOT handle Mono<ServerResponse> or Flux<ServerResponse>.

public boolean supports(HandlerResult result) always return false. because it check a returnValue type of HandlerResult . need to replace a return type with a generic type of it. see below error code.

    @Override
    public boolean supports(HandlerResult result) {
        return (result.getReturnValue() instanceof ServerResponse);
    }

fix like below it has to compare with a generic type of returnType

    @Override
    public boolean supports(HandlerResult result) {
        return ServerResponse.class.isAssignableFrom(result.getReturnType().getGeneric().toClass());
    }

Comment From: hongjunan

i make a PR

https://github.com/spring-projects/spring-framework/pull/27268

Comment From: poutsma

I don't really understand what you mean by handling Flux<ServerResponse>. Such a stream could contain multiple responses, with multiple response codes, headers, and bodies. We can only use one; what do we do with the rest?

And I am not so sure why supporting Mono<ServerResponse> is necessary. In other words: what is the use case here?

Comment From: spring-projects-issues

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

Comment From: hongjunan

Currently, reactive handler cannot handle webflux streaming. Because handler are not checking whether the response value is reactive. Please take a look at the source code I suggested above. The current program is not working properly because of wrong condition checking.

Comment From: snicoll

@hongjunan I am also confused as what you're trying to do and, with a lack of concrete use case, we can't justify spending more time on this issue. If you can provide that information, we can obviously reconsider.