'How to extract response header & status code from Spring 5 WebClient ClientResponse

I am new to Spring Reactive framework & trying to convert Springboot 1.5.x code into Springboot 2.0. I need to return response header after some filtering, body & status code from Spring 5 WebClient ClientResponse. I do not want to use block() method as it will convert it into sync call. I am able to get responsebody pretty easily using bodyToMono. Also, I am getting status code, headers & body if I am just returning ClientResponse but I need to process response based on statusCode & header parameters. I tried subscribe, flatMap etc. but nothing works.

E.g. - Below code will return response Body

Mono<String> responseBody =  response.flatMap(resp -> resp.bodyToMono(String.class));

But similar paradigm is not working to get statusCode & Response headers. Can someone help me in extracting statusCode & header parameters using Spring 5 reactive framework.

javaspringspring-bootspring-webflux


Solution 1:[1]

You can use the exchange function of webclient e.g.

Mono<String> reponse = webclient.get()
.uri("https://stackoverflow.com")
.exchange()
.doOnSuccess(clientResponse -> System.out.println("clientResponse.headers() = " + clientResponse.headers()))
.doOnSuccess(clientResponse -> System.out.println("clientResponse.statusCode() = " + clientResponse.statusCode()))
.flatMap(clientResponse -> clientResponse.bodyToMono(String.class));

then you can convert bodyToMono etc

Solution 2:[2]

I needed to check the response details(headers, status, etc) and body as well.

The only way I was able to do it was by using .exchange() with two subscribe() as the following example:

    Mono<ClientResponse> clientResponse = WebClient.builder().build()
            .get().uri("https://stackoverflow.com")
            .exchange();

    clientResponse.subscribe((response) -> {

        // here you can access headers and status code
        Headers headers = response.headers();
        HttpStatus stausCode = response.statusCode();

        Mono<String> bodyToMono = response.bodyToMono(String.class);
        // the second subscribe to access the body
        bodyToMono.subscribe((body) -> {

            // here you can access the body
            System.out.println("body:" + body);

            // and you can also access headers and status code if you need
            System.out.println("headers:" + headers.asHttpHeaders());
            System.out.println("stausCode:" + stausCode);

        }, (ex) -> {
            // handle error
        });
    }, (ex) -> {
        // handle network error
    });

I hope it helps. If someone knows a better way to do it, please let us know.

Solution 3:[3]

After Spring Boot 2.4.x / Spring 5.3, WebClient exchange method is deprecated in favor of retrieve, so you have to get the headers and response status using ResponseEntity like the following example:

webClient
        .method(HttpMethod.POST)
        .uri(uriBuilder -> uriBuilder.path(loginUrl).build())
        .bodyValue(new LoginBO(user, passwd))
        .retrieve()
        .toEntity(LoginResponse.class)
        .filter(
            entity ->
                entity.getStatusCode().is2xxSuccessful()
                    && entity.getBody() != null
                    && entity.getBody().isLogin())
        .flatMap(entity -> Mono.justOrEmpty(entity.getHeaders().getFirst(tokenHeader)));

Solution 4:[4]

As discussed above, the exchange has been deprecated so we are using retrieve(). This is how I'm returning the code after making a request.

public HttpStatus getResult() {
    WebClient.ResponseSpec response = client
            .get()
            .uri("/hello")
            .accept(MediaType.APPLICATION_JSON)
            .retrieve();

    return Optional.of(response.toBodilessEntity().block().getStatusCode()).get();
}

Another option as per the comment, I've tried recently. This is usually recommended for Async calls but we can use it for both.

MyClass responseMono = this.webClient
                .get()
                .uri("myapipath"}")
                .retrieve()
                .bodyToMono(MyClass.class)
                .block();
        return responseMono;

Solution 5:[5]

For status code you can try this:

Mono<HttpStatus> status = webClient.get()
                .uri("/example")
                .exchange()
                .map(response -> response.statusCode());

For headers:

Mono<HttpHeaders> result = webClient.get()
                .uri("/example")
                .exchange()
                .map(response -> response.headers().asHttpHeaders());

Solution 6:[6]

You can configure spring boot >= 2.1.0 to log request and response if you are using the WebClient: 

spring.http.log-request-details: true
logging.level.org.springframework.web.reactive.function.client.ExchangeFunctions: TRACE

As desribed in the sprint boot docs, if you want headers to be logged, too, you have to add

Consumer<ClientCodecConfigurer> consumer = configurer ->
    configurer.defaultCodecs().enableLoggingRequestDetails(true);

WebClient webClient = WebClient.builder()
    .exchangeStrategies(ExchangeStrategies.builder().codecs(consumer).build())
    .build();

But be aware that this can log sensitve information.

Solution 7:[7]

 httpClient
            .get()
            .uri(url)
            .retrieve()
            .toBodilessEntity()
            .map(reponse -> Tuple2(reponse.statusCode, reponse.headers))

Solution 8:[8]

You can use flatMap to extract the object from Mono

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 dazito
Solution 2 Rafael Amaral
Solution 3 jkamcc
Solution 4
Solution 5
Solution 6 Tobske
Solution 7 Juan Rada
Solution 8 Trippletech Magabe

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