Exception hierarchy under FeignException

[jerzykrlk]

With default error encoder, Feign client will throw FeignException, which is quite general, compared to variety of HTTP error codes and their REST semantics.
In a rest-heavy application, introducing subclasses simplify quite a lot of my code.

Sample piece of code, now:

        try {
            return libraryClient.getBook(1);
        } catch (FeignException e) {
            if (e.status() == 404) {
                // handle the 404 error
            }
            throw e; // can't do anything about other http errors here
        }

And the same piece code, expected:

        try {
            return libraryClient.getBook(1);
        } catch (HttpNotFoundException e) {
            // handle the 404 error
        }

This change seems quite easy, compared ti the code it saves. I could prepare a pull request, if you like the idea.

[navaare]

@jerzykrlk
How much code does it save in fact? Does everybody will be happy with that default behavior? All you need is to define your own exception passing a lot more info at defined ErrorDecoder for feign client.

[jerzykrlk]

Hi,

I think the main benefit would not be less code, but just clener code.

In my apps, there are many places where I catch FeignException, manually check the status code - and if it's something else, rethrow the exception.

For example:

• a call to a remote service returns HTTP 401,
• my code catches FeignException, checks for status 401, reauthenticates,
• otherwise - rethrows the FeignException.

I think it doesn't look good, especially with the same thing repeated in many places in code in many apps.

I already have a custom ErrorDecoder that does that - but I believe it'd be a good add-on to the Default error decoder.

This whole idea is a follow-up of the same feature in Spring RestTemplate - see SPR-15404 and this commit

All HTTP-related exceptions would inherit from FeignException, so the change would be backward compatible.

Could you have a look at #825? - I think it illustrates my idea clearly.

[kdavisk6]

The role of the ErrorDecoder is to allow users to maintain full control. I do see the benefit, but it may not be Feign's place to make this determination across the board for all users nor desired. In practice, we typically do not accept enhancement requests without additional votes. I've marked this issue as such. If it receives enough support, we can consider this more.

[jerzykrlk]

Ok, thank you for the update.

You already have first vote, I guess... :)

[kdavisk6]

Closed via #825