Extend WebClient with createException(HttpStatus code)

[membersound]

It would be nice if you could extend WebClient with createException(HttpStatus code).

Because eg I have an external webservice that I have no control of, and it always returns 200 OK EVEN in case of error responses in body and an error hint in the header.

So when I evaluate the response with a ExchangeFilterFunction, I might want to return a clientResponse.createException(BAD_GATEWAY) based on the received content.

This is impossible by simply calling clientResponse.createException(), which would create a json exception, BUT with status 200 OK proxied through!

In my case, I'd like to write as follows:

private static ExchangeFilterFunction errorHandler() {
	return ExchangeFilterFunction.ofResponseProcessor(clientResponse -> {
                  HttpHeaders headers = clientResponse.headers().asHttpHeaders();
                  return (headers.getFirst("error").equals("true")) 
			? clientResponse.createException(BAD_GATEWAY).flatMap(ex -> Mono.error(ex)) //this is not possible atm
			: Mono.just(clientResponse);
	});
}

[poutsma]

I think you should be able to achieve your goal by using the builder, like so:

if (headers.getFirst("error").equals("true")) {
  return ClientResponse.from(clientResponse)
    .statusCode(BAD_GATEWAY)
    .build()
    .createException()
    .flatMap(ex -> Mono.error(ex));
}
else {
  return Mono.just(clientResponse);
}

[rstoyanchev]

Don't you also need to set the body?

ClientResponse.from(clientResponse)
    .statusCode(BAD_GATEWAY)
    .body(clientResponse.bodyToFlux(DataBuffer.class))
    .build()
    .createException()
    .flatMap(ex -> Mono.error(ex));

[poutsma]

Good point, I forgot that from does not copy the body.

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[membersound]

This is great, but how could I add a custom error text into the WebClientResponseException created with this builder?

[membersound]

It would still be nice if one could just supply a custom statusCode during createException() so that the exception generating code is inherited from ClientResponse, but simply the code is changed. Because bugs are likely being introduced by eg forgetting to set the body, as seen above.