JSON body interaction

[renatolond]

Hey!

I have an issue that I think it's on committee's side, but I'm not sure.

So, I'm using Grape for my API, with rodauth+rodauth-oauth for the auth part.

Here's the issue: with grape reading the body, committee works fine. It seems grape rewinds the body before and after reading it, so it's ready for committee:
https://github.com/ruby-grape/grape/blob/master/lib/grape/middleware/formatter.rb#L86-L92

However, Roda doesn't if rack is >=3. https://github.com/jeremyevans/roda/blob/master/lib/roda/plugins/json_parser.rb#L89-L93

Now, the issue is that since committee does not rewind ahead of reading, it gets an empty body and assumes the lenght == 0 situation (and therefore, no params) and fails the validation: https://github.com/interagent/committee/blob/master/lib/committee/request_unpacker.rb#L81-L83

Adding a rewind before reading solves the issue, but I'm not sure it's the right way to go (I read the Rack spec but it's not clear to me if that rewind is meant to always work).

I thought I could take the grape route and rewind if the input responds to rewind (see #442), wdyt?

[geemus]

@renatolond I'll review the PR soon, but just wanted to provide a little context since I've run into this elsewhere. The challenge is that newer rack expects that the body could actually be a stream (and therefore not rewindable). I believe there is a middleware that is recommended in this case which writes the body to a file and then uses the file (to provide rewinding). I think that or something similar is the recommended safe way forward (as rewinding a stream is always going to break).

Here is the context in which I ran into it and it was vendored (I think maybe the middleware isn't released yet and/or isn't available on older Rack): https://github.com/ubicloud/ubicloud/blob/a2013ad31991e8ef526755471f5a3cb6d61e82ec/clover.rb#L18

Does that help clarify the situation?

[renatolond]

Hmm, that does seem to solve the lack of .rewind, but I don't have that issue here. I'm not sure if it's because of my combination of gems, but I have .rewind, my issue is more that the IO has already been used by roda and not rewinded before used by committee. 🤔

[geemus]

@renatolond Yes, sorry if that was unclear. The problem is more about doing this in a way that would still work for cases where there isn't rewind. So not so much solving your problem as avoiding creating new problems by solving this one. Does that make more sense?

And furthermore, the reason roda doesn't rewind is to avoid breaking things for streams (as suggested above). This was a more recent change, based on changes to Rack which allow for streams in that context in the first place.