Rails OutputCompressionFilter

The Rails documentation has passing references to a filter class called OutputCompressionFilter. However, this code is nowhere to be found.

Since I have some code to do output compression (see my earlier post), I decided to repackage it as this class:

require 'stringio'
require 'zlib'

class OutputCompressionFilter

  # Do output compression if the client supports it
  def self.filter(controller)
    if controller.request.env['HTTP_ACCEPT_ENCODING'].match(/gzip/)
      if controller.response.headers["Content-Transfer-Encoding"] != 'binary'
        begin
          controller.logger.info "Compressing"
          ostream = StringIO.new
          gz = Zlib::GzipWriter.new(ostream)
          gz.write(controller.response.body)
          controller.response.body = ostream.string
          controller.response.headers['Content-Encoding'] = 'gzip'
        ensure
          gz.close if gz
        end
      end
    end
  end

end

Here is the source file – put it in your lib directory.

Here is how you use this code:

require "compress.rb"

class ApplicationController < ActionController::Base
  after_filter OutputCompressionFilter
  ...
end

This code works just like the Rails Filter documentation indicates.

Update: I’ve updated the source file to include the major updates in the comments from Dan, and my updates to that code.

This entry was posted on Sat, 17 Dec 2005 20:35:00 GMT . You can follow any any response to this entry through the Atom feed. You can leave a comment or a trackback from your own site.


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  1. Jason Barnabe &raquo; Blog Archive &raquo; Rails, bandwidth, and HTTP content encoding about 1 year later:

    [...] Having it turned on in Apache is ideal because then it’ll affect static content as well, but there are ways to do it in Rails (and probably other languages, but I only care about Rails). Courtesy Tom Fakes, here are short and sweet instructions. [...]

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