accept format query parameter like rails to steer the response format

[neetiraj]

This emulates the Rails behavior of identifying the expected response format from format query parameter if available. With this resolution Grape would be able to decipher that the expected response format is json from a URL like this - http://myblog.com/updates?format=json. This is from an issue that I reported in Grape google group - https://groups.google.com/forum/?fromgroups=#!topic/ruby-grape/uUFd-OcNwDM where the solution was accepted and suggested to do git pull for the same.

[dblock]

Doesn't params[:format] have what you want? Instead of parsing QUERY_STRING?

[dblock]

This also needs a README and a CHANGELOG update, please.

[neetiraj]

I agree, params[:format] would be a much better solution than parsing QUERY_STRING. I am quite new to Rack stuff and params[:format] OR request.params[:format] OR env['rack.request.params'] is not giving me the query parameter.

[dblock]

I did 5 seconds of research. Looks like Rack::Request has a query_string, which looks at ENV, but probably should be the one used. Then I think we need to use a proper URL parser (URI? CGI?) here to extract this stuff.

When I have a moment, I'll play with it, but feel free to make additional pulls here.

[dblock]

I merged this change and rewrote the QUERY_STRING parser to use Rack::Utils (found via this SO q/a). Double-check my diff please.

Thanks for contributing!

[neetiraj]

@dblock Rack::Utils query string parsing is quite an elegant solution. Thanks for guiding towards a cleaner approach.