Ruby on Rails 3: Streaming data through Rails to client

Question

Hi,

I am working on a Ruby on Rails app that communicates with RackSpace cloudfiles (similar to Amazon S3 but lacking some features).

Due to the lack of the availability of per-object access permissions and query string authentication, downloads to users have to be mediated through an application.

In Rails 2.3, it looks like you can dynamically build a response as follows:

# Streams about 180 MB of generated data to the browser.
render :text => proc { |response, output|
  10_000_000.times do |i|
    output.write("This is line #{i}\n")
  end
}

(from http://api.rubyonrails.org/classes/ActionController/Base.html#M000464)

Instead of 10_000_000.times... I could dump my cloudfiles stream generation code in there.

Trouble is, this is the output I get when I attempt to use this technique in Rails 3.

#<Proc:0x000000010989a6e8@/Users/jderiksen/lt/lt-uber/site/app/controllers/prospect_uploads_controller.rb:75>

Looks like maybe the proc object's call method is not being called? Any other ideas?

Answer 1

It looks like this isn't available in Rails 3

https://rails.lighthouseapp.com/projects/8994/tickets/2546-render-text-proc

This appeared to work for me in my controller:

self.response_body =  proc{ |response, output|
  output.write "Hello world"
}

Answer 2

Yes, response_body is the Rails 3 way of doing this for the moment: https://rails.lighthouseapp.com/projects/8994/tickets/4554-render-text-proc-regression