read grid files

GridfsController.rb

require 'mongo'

class GridfsController < ActionController::Metal
  def serve
    env["PATH_INFO"].match(/\/attach\/([\da-zA-Z]+)\//)
    begin
      grid = Mongo::Grid.new(Mongoid.database).get(BSON::ObjectId($1))
      self.headers["Content-Length"] = grid.file_length.to_s
      self.content_type = grid.content_type
      self.response_body = grid.read
    rescue
      self.status = :file_not_found
      self.content_type = 'text/plain'
      self.response_body = ''
    end
  end
end