#859 Add error-handling best practice in quickstart-se

[camerondurham]

Closes my issue #859 in examples/quickstarts/helidon-quickstart-se

[romain-grecourt]

Hi @camerondurham, the version change part of your PR is not valid.
I'll let other people chime in regarding the exception handling change.

The examples in the master branch depend on the current SNAPSHOT version and thus require a full build.
If you wish to try-out examples for a given release, you can follow the instructions documented here: https://github.com/oracle/helidon/blob/master/examples/README.md

[camerondurham]

HI @romain-grecourt , thank you for the update. Should I instead remove this request and make only the .exceptionally(...) fix?

[romain-grecourt]

Yes, go ahead.

[camerondurham]

@romain-grecourt My PR now only updates the quickstart.

[romain-grecourt]

There are a couple of issues with your suggested change.

1. If you submit invalid JSON, it would also return a 400 with "empty body"
2. A good practice would be to show the use of request.next(throwable) to delegate the error to error handlers.

Here is what I came up with:

        request.content().as(JsonObject.class)
                .thenAccept(jo -> updateGreetingFromJson(jo, response))
                .exceptionally((Throwable ex) -> {
                    if (ex.getCause() instanceof JsonException) {
                        request.next(new BadRequestException("Invalid JSON",
                                (JsonException) ex.getCause()));
                    } else {
                        request.next(ex);
                    }
                    return null;
                });

@tomas-langer thoughts ?

[camerondurham]

Thanks for pointing out those issues. Of course, I agree that your change is much more effective. Sorry for being unfamiliar with this process, but would you be making this change yourself or should I modify my PR? @romain-grecourt

[romain-grecourt]

Ideally you'd make this change in your PR so that you could get a Helidon contrib under your Belt.

[romain-grecourt]

@barchetta @tomas-langer Any thoughts on the suggested changes ?

[camerondurham]

Thanks, that sounds great. I'm adding @namanshenoy to my fork since he's another Oracle employee I worked with on this.

[romain-grecourt]

@tomas-langer What do you think about returning the exception message in the response body ?

[romain-grecourt]

Sorry, I approved by mistake ; the error handling needs to be refined.

[romain-grecourt]

LGTM, @tomas-langer @barchetta can you guys take a look ?

[tomas-langer]

LGTM