@guilleiguaran Thank you for the PR.

Question, based of the code in Rack::ContentLength. If the body is an Array (responds to to_ary), should it be treated as a 'non-chunked' body?

IOW, if body is an Array, we compute the Content-Length. If the body isn't an Array or an IO/File (responds to read, etc), we consider it chunked, and handle it via each.

Thoughts? Making this change would require changing some tests, as many tests assume body arrays are chunked unless they contain one element. Using Array#to_enum probably fixes all of them...

@MSP-Greg sorry for the delay, I've been working back and forth with multiple implementations of this, the current one handles array bodies with more than one element, Rack::BodyProxy, and also Rails' RackBody. Probably this needs to be updated to handle File-like objects as well (checking for to_path I guess?)

Rails' ActionDispatch::Response::RackBody (introduced 8 years ago in 4.2) responds to_ary just to conform with the implementation of Rack::ContentLength at the time in Rack 1.6, but it returns nil since Rack::ContentLength used #each without calling to to_ary. Rack 2.2 stopped checking for to_ary and Rack 3.0 (master) once again checks for to_ary and actually calls it.

There have been many discussions around how to decide if a body should be considered to have a knowable length or not in both Rack and Rails, see:

rails/rails#16793
rack/rack#734
rack/rack@9495207
rack/rack#1748
rack/rack#1509
rails/rails#44953

@guilleiguaran

sorry for the delay

No problem.

Thanks for all the links. The 'returns nil' code is interesting, to put it nicely.

I wonder why an app would not set Content-Length if the body had a knowable length. That aside, I wonder if something like the following would get around all the issues? Note, I need a refresh based on your above comments...

if (app_body.respond_to?(:to_ary) && (body = app_body.to_ary)) ||
    (app_body.is_a?(Array) && app_body.all? { |el| el.is_a? String } && body = app_body)
  # compute length from body, use body to write response
end

app_body is the body returned by the app, currently called res_body.

@guilleiguaran

Dumb Rails question:

Would a normal Rails app ever return a body where body.is_a? Array is true, or, better yet, body.class == Array is true?

@MSP-Greg no for anything handled through ActionDispatch (e.g Rails controllers), those are always wrapped in ActionDispatch::Response::RackBody

For the next version of Rails, I'll work in proper support for Rack 3.0 and Rack::ContentLength (supporting to_ary for real, not returning nil)