How to use #ControllerAdvice to handle webclient errors from the reactive stack (web flux -> spring) - spring-boot

Question

I use webclient from weblux to send a request to a remote server. At this point, I can get error 400. I need to intercept it and send it to the client.
webClient
.post()
.uri(
)
.contentType(MediaType.APPLICATION_FORM_URLENCODED)
.body(
BodyInserters
.fromFormData()
.with()
.with()
)
.retrieve()
.onStatus(
HttpStatus::isError, response -> response.bodyToMono(String.class) // error body as String or other class
.flatMap(error -> Mono.error(new WrongCredentialsException(error)))
)
.bodyToMono(TResponse.class)
.doOnNext(...);
error
#ControllerAdvice
#Slf4j
public class ApplicationErrorHandler {
#ExceptionHandler(WrongCredentialsException.class)
public ResponseEntity<ErrorResponse> handleResponseException(WrongCredentialsException ex) {
// log.error("Error from WebClient - Status {}, Body {}", ex.getRawStatusCode(), ex.getResponseBodyAsString(), ex);
ErrorResponse error = new ErrorResponse();
return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
.body(error);
}
#Data
#NoArgsConstructor
#AllArgsConstructor
public class ErrorResponse {
private String errorCode;
private String message;
}
rest api
#PostMapping
public ResponseEntity<String> send(#RequestBody Dto dto) {
log.debug("An notification has been send to user");
return new ResponseEntity<>(HttpStatus.OK);
}
I tried the options from here, but it didn't work out . Can someone explain how it works and how it can be configured for my case?

Answer 1

first case
return Objects.requireNonNull(oauthWebClient
.post()
.uri(uri)
.bodyValue(dto)
.attributes(oauth2AuthorizedClient(authorizedClient))
.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
.exchangeToMono(response -> {
HttpStatus httpStatus = response.statusCode();
if (httpStatus.is4xxClientError()) {
getErrFromClient(response, httpStatus);
}
if (httpStatus.is5xxServerError()) {
getErrFromServer(response, httpStatus);
}
return Mono.just(ResponseEntity.status(response.statusCode()));
})
.block())
.build();
}
private void getErrFromServer(DtoResponse response, HttpStatus httpStatus) {
String err = response.bodyToMono(String.class).toString();
log.error("HttpStatus: {}, message: {}", httpStatus, err);
HttpHeaders httpHeaders = response.headers().asHttpHeaders();
List<String> errorBody = httpHeaders.get("errBody");
assert errBody != null;
throw new CustomException(
"{ HttpStatus : " + httpStatus + " , message : " + errBody + " }");
}
private void getErrFromClient(DtoResponse response, HttpStatus httpStatus) {
String err = response.bodyToMono(String.class).toString();
log.error("HttpStatus: {}, err: {}", httpStatus, err);
HttpHeaders httpHeaders = response.headers().asHttpHeaders();
List<String> errorBody = httpHeaders.get("errBody");
assert errBody != null;
throw new CustomException(
"{ HttpStatus : " + httpStatus + " , message : " + errBody + " }");
}
and than
#ControllerAdvice
public class HandlerAdviceException {
#ExceptionHandler(CustomException.class)
public ResponseEntity<ErrorResponse> handleCustomException(CustomException e) {
//here your code
//for example:
String errMessage = e.getLocalizedMessage();
return ResponseEntity
.internalServerError()
.body(new ErrorResponse(ErrorCode.INTERNAL_ERROR, errMessage));
}
}
second case
return webClient
.post()
.uri(
properties......,
Map.of("your-key", properties.get...())
)
.contentType(MediaType.APPLICATION_FORM_URLENCODED)
.body(
prepare....()
)
.retrieve()
.bodyToMono(TokenResponse.class)
.doOnSuccess(currentToken::set);
}
Here, if successful, you will get the result you need, but if an error occurs, then you only need to configure the interceptor in the Advice Controller for WebClientResponseException.
#ControllerAdvice
#Slf4j
public class CommonRestExceptionHandler extends ResponseEntityExceptionHandler {
#ExceptionHandler(WebClientResponseException.class)
protected ResponseEntity<ApiErrorResponse> handleWebClientResponseException(WebClientResponseException ex) {
log.error(ex.getClass().getCanonicalName());
String errMessageAdditional = .....
final ApiErrorResponse apiError = ApiErrorResponse.builder()
.message(ex.getLocalizedMessage())
.status(HttpStatus.UNAUTHORIZED)
.build();
//if it needs
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.add(.......);
return new ResponseEntity<>(apiError, httpHeaders, apiError.getStatus());
}
}