Spring WebFlux: How to access Request Body in HandlerFilterFunction

Question

I'm trying to access the request body from WebFlux's HandlerFunctionFunction but I am getting java.lang.IllegalStateException: Only one connection receive subscriber allowed. .

I want to do something similar to below code block

public class ExampleHandlerFilterFunction 
  implements HandlerFilterFunction<ServerResponse, ServerResponse> {

    @Override
    public Mono<ServerResponse> filter(ServerRequest serverRequest,
      HandlerFunction<ServerResponse> handlerFunction) {
        if (serverRequest.pathVariable("name").equalsIgnoreCase("test")) {
            return serverRequest.bodyToMono(Player.class)
             .doOnNext(loggerService :: logAndDoSomethingElse)
             .then(handlerFunction.handle(serverRequest);
        }
        return handlerFunction.handle(serverRequest);
    }
}

I tried serverRequest.bodyToMono(Player.class).cache() too, but did not work.

Update: Adding handler and router functions

Handler Function

@Component
public class PlayerHandler {

    @Autowired
    private final playerRepository;

    public PlayerHandler(PlayerRepository palyerRepository) {

       this.palyerRepository = playerRepository;
    }

    public Mono<ServerResponse> savePlayer(ServerRequest request) {

        Mono<String> id = request.bodyToMono(Player.class)
        .map(playerRepository::save)
        .map(Player::getId);

        return ok().body(id, String.class);
    }
}

Router function

@Bean
public RouterFunction<ServerResponse> route(PlayerHandler playerHandler) {
    return RouterFunctions
      .route(POST("/players/"), playerHandler::save)
      .filter(new ExampleHandlerFilterFunction());
}

Logger service

public Mono<Void> T logAndDoSomethingElse(T t){
    ---- auditing business logic----
    return loggerRepository.save(asJsonb);
}

Can someone help me? Thanks

Answer 1

import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.server.HandlerFilterFunction;
import org.springframework.web.reactive.function.server.HandlerFunction;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import reactor.core.publisher.Mono;

@Component
public class FundsAuthorizationFilter implements HandlerFilterFunction<ServerResponse, ServerResponse> {

    @Override
    public Mono<ServerResponse> filter(ServerRequest request, HandlerFunction<ServerResponse> handlerFunction) {
        String block = request.bodyToMono(String.class).block();
        JSONObject jsonObj = new JSONObject(block);
        ServerRequest.Builder newRequestBuilder = ServerRequest.from(request);
        newRequestBuilder.body(block);

        return handlerFunction.handle(newRequestBuilder.build());
    }

}

I found a solution for this, that is clone the serverRequest and set the body to the new request