Patch for Mongo::GridIO to respond to each as required by the Rack API.

config.ru

# Patch Mongo::GridIO to contain an each method.
require File.join File.dirname(__FILE__), 'lib/kimono/grid_io'
Mongo::GridIO.send(:include, Kimono::GridIO)

# You probably want to implement something a bit smarter than just talking
# to localhost.
database = Mongo::Connection.new.db('kimono_production')

app = proc do |env|
  begin
    gridfs_file = Mongo::GridFileSystem.new(Mongoid.database).open(env["PATH_INFO"], 'r')
    [ 200, { 'Content-Type' => gridfs_file.content_type, 'Content-Length' => gridfs_file.file_length.to_s }, gridfs_file ]
  rescue
    message = 'Grid file not found.'
    [ 404, { 'Content-Type' => 'text/plain', 'Content-Length' => message.size.to_s }, message ]
  end
end

run app

grid_io.rb

require 'mongo'

module Kimono
  module GridIO

    def size
      (file_length / chunk_size) + (file_length % chunk_size > 0 ? 1 : 0)
    end

    def each
      size.times { yield read(chunk_size) }
    end
 
  end
end

jeremys_original_gridfs_controller.rb

require 'mongo'
        
class GridfsController < ActionController::Metal
  def serve
    gridfs_path = env["PATH_INFO"].gsub("/images/", "")
    begin
      gridfs_file = Mongo::GridFileSystem.new(Mongoid.database).open(gridfs_path, 'r')
      self.response_body = gridfs_file.read
      self.content_type = gridfs_file.content_type
    rescue
      self.status = :file_not_found
      self.content_type = 'text/plain'
      self.response_body = ''
    end
  end
end

routes.rb

Kimono::Application.routes.draw do

  # Patch Mongo::GridIO to contain an each method.
  require File.join Rails.root, 'lib/kimono/grid_io'
  Mongo::GridIO.send(:include, Kimono::GridIO)
  match "/gridfs/*path", :via => :get, :to => proc { |env|
    gridfs_path = env["PATH_INFO"].gsub("/gridfs/", "")
    begin
      gridfs_file = Mongo::GridFileSystem.new(Mongoid.database).open(gridfs_path, 'r')
      [ 200, { 'Content-Type' => gridfs_file.content_type, 'Content-Length' => gridfs_file.file_length.to_s }, gridfs_file ]
    rescue
      message = 'Grid file not found.'
      [ 404, { 'Content-Type' => 'text/plain', 'Content-Length' => message.size.to_s }, message ]
    end
  }


end

In answer to your first question, probably because I have three small kids and don't get enough sleep :)

You're right about yield, I tend to think of the block as a method argument so prefer to see it visually in the method signature. I'll change it ASAP.

These are dumb mistakes. So is your tone. I'm letting it slide.

OK.

I know it sounded harsh, I'm sorry. But these are the kind of mistakes that shouldn't happen anymore given how well Ruby is documented now.