Kotlin Spring Reactive Webflux - Handle WebClient Error - spring-boot

Question

I am having troubles trying to handle different errors from calling Spring webflux's web client.
Below is my current code.
return request
.bodyToMono(InputMessage::class.java)
.flatMap { inputMessage ->
client
.get()
.uri { builder ->
builder.path("/message")
.queryParam("message", inputMessage.message)
.build()
}
.retrieve()
.onStatus({t: HttpStatus -> t.is5xxServerError}, {c: ClientResponse -> Mono.error(Throwable("Internal Server Error - try again later"))})
.bodyToMono(ListOfAddresses::class.java)
}
.flatMap { s -> ServerResponse.ok().syncBody(s) }
If it errors, it is still returning the full error message from the client's call.
I tried something else, like this
return request
.bodyToMono(InputMessage::class.java)
.flatMap { inputMessage ->
client
.get()
.uri { builder ->
builder.path("/message")
.queryParam("message", inputMessage.message)
.build()
}
.retrieve()
.onStatus({t: HttpStatus -> t.is5xxServerError}, {c: ClientResponse -> Mono.error(Throwable("Internal Server Error - try again later"))})
.bodyToMono(ListOfAddresses::class.java)
}
.flatMap { s -> ServerResponse.ok().syncBody(s) }
.onErrorResume { e -> Mono.just("Error " + e.message)
.flatMap { s -> ServerResponse.ok().syncBody(s) } }
It actually works but then I want to handle different Http status codes error (different messages for each Http status code).
How can I modify my code so it will return the custom message I build?

Answer 1

As per WebFlux documentation, you can user the exchangeToMono() or awaitExchange { } in order to have an error handling.
Mono<Object> entityMono = client.get()
.uri("/persons/1")
.accept(MediaType.APPLICATION_JSON)
.exchangeToMono(response -> {
if (response.statusCode().equals(HttpStatus.OK)) {
return response.bodyToMono(Person.class);
}
else if (response.statusCode().is4xxClientError()) {
// Suppress error status code
return response.bodyToMono(ErrorContainer.class);
}
else {
// Turn to error
return response.createException().flatMap(Mono::error);
}
});
Code copied from WebFlux link above.

Answer 2

Take a look at 2.3. Exchange
val entity = client.get()
.uri("/persons/1")
.accept(MediaType.APPLICATION_JSON)
.awaitExchange {
if (response.statusCode() == HttpStatus.OK) {
return response.awaitBody<Person>()
}
else if (response.statusCode().is4xxClientError) {
return response.awaitBody<ErrorContainer>()
}
else {
throw response.createExceptionAndAwait()
}
}