I'm using Spring webflux in my project for communicating with external API.
In my project I'm not able to convert Flux to List.
On trying to do the same with collectList().block() all the elements of the flux gets concatenated to a single string and gets stored at 0th index of list.
If I return the Flux instead of List then it sends the expected response. But I need to manipulate the contents and add it as a child to other object & therefore trying to return the List.
public List<String> retrieveWebLogin(String platformId) {
try {
ClientResponse response = webClient
.get()
.uri(EV_LEGACY_WEB_RTC_ENDPOINT_API_PATH)
.accept(APPLICATION_JSON)
.exchange().block();
Flux<String> uriFlux = response.bodyToFlux(String.class);
List<String> uriList = uriFlux.collectList().block();
return uriList;
} catch (Exception e) {
logger.info(e.getMessage(), e);
}
return null;
}
Expected result:
[
"agent1",
"agent2"
]
Actual Result:
"["agent1","agent2"]"
You code should look like this instead.
final List<String> uriList = webClient
.get()
.uri(EV_LEGACY_WEB_RTC_ENDPOINT_API_PATH)
.accept(MediaType.APPLICATION_JSON_UTF8)
.exchange()
.flatMap(response -> response.bodyToMono(new ParameterizedTypeReference<List<String>>() {}))
.block();
Related
I want to call a microservice from another service using webclient in spring flux. But, I am not able to write the code properly. Can you please suggest how to call another service. Please find my code as below.
I need to call the below service
public Mono<ServerResponse> load(ServerRequest res){
String c1name = res.pathVariable("cust");
String c2name = res.queryParam("cl").orElse("");
String oname = res.queryParam("ol").orElse("");
return res.body()
}
public Mono<ResponseEntity<Void>> ftpFileSend(MultipartFile fileData, String cust, MultiValueMap<String,String) qpar {
MultiValueMap<String,String> qpar=new LinkedMultiValueMap<String,String>();
qpar.add("name","spring");
MultiValueMap<String,Object> body=new LinkedMultiValueMap<String,Object>();
String url="http://localhost:8088/"+ cust+"/load";
try {
body.add("file", fileData.getBytes());
} catch (IOException e) {
return Mono.error(e); // <-- note how to create an error signal
}
return webClient
.post()
.uri(uriBuilder -> uriBuilder.path(url).queryParams(qpar).build() )
.contentType(MediaType.MULTIPART_FORM_DATA)
.body(BodyInserters.fromMultipartData(body))
.retrieve()
.toBodilessEntity();
}
Hmm it would be great if you have provided some error logs or so. Anyway if you want to create a multipart body there is a builder, MultipartBodyBuilder (in org.springframework.http.client.MultipartBodyBuilder).
Example usage is as follows,
MultipartBodyBuilder builder = new MultipartBodyBuilder();
builder.part("file", new MultipartFileResource(fileData));
MultiValueMap<String, HttpEntity<?>> multipartBody = builder.build();
Then use this multipartBody in webClient call.
return webClient
...
.body(BodyInserters.fromMultipartData(multipartBody))
.retrieve()
.toBodilessEntity();
i'm trying to send a POST request with body data as described here: https://scrapyrt.readthedocs.io/en/stable/api.html#post.
Here's what i've tried to do but it gives me HTTP code 500
String uri = "http://localhost:3000";
WebClient webClient = WebClient.builder()
.baseUrl(uri)
.build();
LinkedMultiValueMap map = new LinkedMultiValueMap();
String q = "\"url\": \"https://blog.trendmicro.com/trendlabs-security-intelligence\",\"meta\":{\"latestDate\" : \"18-05-2020\"}}";
map.add("request", q);
map.add("spider_name", "blog");
BodyInserter<MultiValueMap<String, Object>, ClientHttpRequest> inserter2
= BodyInserters.fromMultipartData(map);
Mono<ItemsList> result = webClient.post()
.uri(uriBuilder -> uriBuilder
.path("/crawl.json")
.build())
.body(inserter2)
.retrieve()
.bodyToMono(ItemsList.class);
ItemsList tempItems = result.block();
Here's what i've tried to do but it gives me HTTP code 500
Most likely because you're sending the wrong data in a mixture of wrong formats with the wrong type:
You're using multipart form data, not JSON
You're then setting the request parameter as a JSON string (q)
The JSON string you're using in q isn't even valid (it's at least missing an opening curly brace) - and handwriting JSON is almost universally a bad idea, leverage a framework to do it for you instead.
Instead, the normal thing to do would be to create a POJO structure that maps to your request, so:
public class CrawlRequest {
private CrawlInnerRequest request;
#JsonProperty("spider_name")
private String spiderName;
//....add the getters / setters
}
public class CrawlInnerRequest {
private String url;
private String callback;
#JsonProperty("dont_filter")
private String dontFilter;
//....add the getters / setters
}
...then simply create a CrawlRequest, set the values as you wish, then in your post call use:
.body(BodyInserters.fromValue(crawlRequest))
This is a rather fundamental, basic part of using a WebClient. I'd suggest reading around more widely to give yourself a better understanding of the fundamentals, it will help tremendously in the long run.
For me following code worked:
public String wcPost(){
Map<String, String> bodyMap = new HashMap();
bodyMap.put("key1","value1");
WebClient client = WebClient.builder()
.baseUrl("domainURL")
.build();
String responseSpec = client.post()
.uri("URI")
.headers(h -> h.setBearerAuth("token if any"))
.body(BodyInserters.fromValue(bodyMap))
.exchange()
.flatMap(clientResponse -> {
if (clientResponse.statusCode().is5xxServerError()) {
clientResponse.body((clientHttpResponse, context) -> {
return clientHttpResponse.getBody();
});
return clientResponse.bodyToMono(String.class);
}
else
return clientResponse.bodyToMono(String.class);
})
.block();
return responseSpec;
}
hoping someone can steer me in the right direction in turning my code into a more reactive service call. for background I have a preceding function that will generate a list of users, will then use that list to call this getUserDetails function for each user in the list, and return a map or list of user + details.
#HystrixCommand(commandKey = "getUserDetails")
public getUserResponse getUserDetails(userRequest request) {
getUserResponse response = webClient.post()
.uri(uri)
.body(BodyInserters.fromObject(request))
.retrieve()
.onStatus(HttpStatus::isError, resp -> resp.bodyToMono(getUserError.class).map(errorHandler::mapRequestErrors))
.bodyToMono(getUserResponse.class).block();
return response;
}
Ideally I would also replace/remove the error mapping as only concerned with logging the returned error response and continuing.
so far I have thought something along the lines of this but I'm not sure the webflux/hystrix will play nice?
#HystrixCommand(commandKey = "getUserDetails", fallbackMethod = "getUserFallback")
public Mono<getUserResponse> getUserDetails(userRequest request) {
return = webClient.post()
.uri(uri)
.body(BodyInserters.fromObject(request))
.retrieve()
.bodyToMono(getUserResponse.class);
}
#HystrixCommand
public Mono<getUserResponse> getUserFallback(userRequest request, Throwable throwable) {
log.error(//contents of error message returned)
return mono.empty();
}
public Flux<UserMap> fetchUserDetails(List<Integer> userIds) {
return Flux.fromIterable(userIds)
.parallel()
.runOn(Schedulers.elastic())
.flatMap(userDetailsRepository::getUserDetails);
}
Hystrix is deprecated. If you have a chance, move to resilience4j which has support for Webflux/Reactor.
Spring also has dedicated support for resilience4j.
Regarding error handling you can leverage the rich set of operators from the Mono/Flux API like onErrorReturn or onErrorResume.
We are planing to migrate from spring Rest-Template to Reactor-webclient.
With Rest-template we have written custom logging interceptors where we were printing request and response with uniqueId, before desrialization.
Now weblient provide filters, but in filters I can't access responseBody to log it.
We have some third party APIs where they send strings in case of error and some objects in case of success. In this case I can't wait to log response after deserialization, because it will break and we will not be able to log what response we got.
You can try creating a wrapper WebClient which will first log the response and then will deserialize.
The success response will fall on doOnSuccess and the error will fall on onErrorResume.
public <T> Mono<T> get(String url, Map<String, String> headersMap, Class<T> type) {
Mono<T> responseMono = client.get().uri(url).headers((h) -> headersMap.forEach(h::set)).retrieve()
.bodyToMono(type);
return responseMono.doOnSuccess(response -> log.debug("REST GET call to {} is successfull and response is {}",
url,response).onErrorResume(err -> {
log.error("Exception occurred calling get({}): {}", url,
err.getMessage());
return Mono.error(err);
});
}
Here is some sudo code for something I use to test with:
WebClient client = WebClient.create("www.google.com");
ObjectMapper mapper = new ObjectMapper();
client.get()
.retrieve()
.bodyToMono(String.class)
.map(rawBody -> {
try {
return mapper.readValue(rawBody, Response.class);
} catch (JsonProcessingException e) {
throw new RuntimeException("Cannot deserialize string: " + rawBody);
}
});
I would like to put a case where if object exist then send error if not then create new user.
here is my handler:
public Mono<ServerResponse> createUser(ServerRequest request) {
Mono<UserBO> userBOMono = request.bodyToMono(UserBO.class);
Mono<String> email = userBOMono.map(UserBO::getEmail);
Mono<User> userMono = email.flatMap(userRepository::findByEmail);
return userMono.flatMap(user -> {
Mono<ErrorResponse> errorResponseMono = errorHanlder.handleEmailAlreadyExist();
return ServerResponse.status(HttpStatus.CONFLICT)
.contentType(MediaType.APPLICATION_JSON)
.body(errorResponseMono, ErrorResponse.class);
}).switchIfEmpty(Mono.defer(() -> {
Mono<User> newUserMono = userBOMono.flatMap(userMapping::mapUserBOToUser);
Mono<User> dbUserMono = newUserMono.flatMap(userRepository::save);
return ServerResponse.status(HttpStatus.CREATED)
.contentType(MediaType.APPLICATION_JSON)
.body(dbUserMono, User.class);
}));
if Mono is not empty then its return conflict that what I want if if empty then create new but its throwing below error:
java.lang.IllegalStateException: Only one connection receive subscriber allowed.
at reactor.ipc.netty.channel.FluxReceive.startReceiver(FluxReceive.java:276) ~[reactor-netty-0.7.8.RELEASE.jar:0.7.8.RELEASE]
at reactor.ipc.netty.channel.FluxReceive.lambda$subscribe$2(FluxReceive.java:127) ~[reactor-netty-0.7.8.RELEASE.jar:0.7.8.RELEASE]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:163) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:464) ~[netty-transport-4.1.27.Final.jar:4.1.27.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_131]
Update Note: its correct behavior as per method definition:
switchIfEmpty(Mono<? extends T> alternate)
Fallback to an alternative Mono if this mono is completed without data
Means when I am sending empty Mono in body its work fine:
return ServerResponse.status(HttpStatus.CREATED)
.contentType(MediaType.APPLICATION_JSON)
.body(Mono.empty(), User.class);
so what is solution to handle swtichIfEmpty case if I would like to send Mono object as return from it.
Finally I was able to resolve it, I was reading userBOMono stream twice which was causing this error to throw by webflux.
so here is updated code which works fine.
public Mono<ServerResponse> createUser(ServerRequest request) {
Mono<UserBO> userBOMono = request.bodyToMono(UserBO.class);
return userBOMono.flatMap(userBO -> {
String email = userBO.getEmail();
Mono<User> userMono = userRepository.findByEmail(email);
return userMono.flatMap(user -> errorHandler.handleEmailAlreadyExist())
.switchIfEmpty(Mono.defer(() -> createNewUser(userBO)));
});
}
private Mono<ServerResponse> createNewUser(UserBO userBO) {
Mono<User> userMono = Mono.just(userBO).flatMap(userMapping::mapUserBOToUser).flatMap(userRepository::save);
return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON)
.body(userMono, User.class);
}
I assume you use a WebClient to invoke this API.
The client should not subscribe more than once, otherwise this error can come.
I've got the same error by running my #SpringBootTest class.
The problem seems to be that response was being writed while methods had already been closed.
Solved by passing "Mono.empty()" instead of full response.
Code Before:
WebClient.create()
.get()
.uri(new URI(UPDATE_COMPANIES_URL))
.exchangeToMono(response -> {
if (response.statusCode().equals(HttpStatus.OK)) {
return response.bodyToMono(Boolean.class).thenReturn(Boolean.TRUE);
} else {
System.out.println("[sendSecureRequest] Error sending request: " + response.statusCode());
return response.bodyToMono(Boolean.class).thenReturn(Boolean.FALSE);
}
}).subscribe();
Code After:
WebClient.create()
.get()
.uri(new URI(UPDATE_COMPANIES_URL))
.exchangeToMono(response -> {
if (response.statusCode().equals(HttpStatus.OK)) {
// TODO handle success
} else {
System.out.println("[sendSecureRequest] Error sending request: " + response.statusCode());
}
return Mono.empty();
}).subscribe();