Compression Middleware needs to check status code

[RXminuS]

Right now the compression middleware compresses any response and subsequently writes a 200 status code. However if for instance a 400 is returned we want to not send a 200 status code down; other compression middlewares seem to not compress if this is the case.

[RXminuS]

For instance here: https://github.com/goadesign/goa/blob/4a2fb392efdacbce01a1b5f86826253ca5c3e97c/middleware/gzip/middleware.go#L330

[pkieltyka]

@RXminuS good catch and thx for the report

[RXminuS]

@pkieltyka I posted a quick'n dirty fix :-)

[RXminuS]

...mmm actually, there seems to be something else going on as well :-/ I need to investigate more

[RXminuS]

AH! defer w.WriteHeader(code) doesn't work... defer w.ResponseWriter.WriteHeader(code) DOES work...don't quite understand why though, must be something that goes wrong in the encapsulation...

[RXminuS]

My best guess is because of the naming conflict (overloading the WriteHeader method)...similar to what they are discussing here https://stackoverflow.com/questions/38513779/extending-golangs-http-responsewriter-functionality-to-pre-post-process-respons

[AdamHepner]

Ohhh, this had me going chase my tail for days now!

If this is any consolation, here's a minimal reproduction: https://gist.github.com/AdamHepner/03b9addac10c47534bd3392cb0e069e1

[anurag]

This issue will probably going to cause a lot of people a lot of pain if they upgrade to v4. Perhaps worth pointing out in the release notes until it's fixed?

[lrstanley]

Agreed -- this completely breaks redirects if I load the compression middleware.

[pkieltyka]

fixed in 1a6bb10 -- thanks for the tip on the fix @RXminuS -- I'm not sure why this works, but I've tested it and resolves the issue

[VojtechVitek]

Released in https://github.com/go-chi/chi/tree/v4.0.1.