mongoid per id cache

gistfile1.rb

module Mongoid #:nodoc:
  module Cache
    extend ActiveSupport::Concern

    included do
			class << self
				alias_method :original_find, :find
				def find_with_cache(*args)					
					if args.length == 1 and (args[0].is_a? BSON::ObjectId or args[0].is_a? String)
						Rails.cache.fetch("#{self.name}::#{args[0].to_s}") {find_without_cache *args}
					else
						find_without_cache *args
					end
				end
				alias_method_chain :find, :cache
			end

			before_update :invalidate_cache
			before_destroy :invalidate_cache
    end

		def InstanceMethods
			def invalidate_cache
				self.class.query_cache.delete id.to_s
			end			
		end
  	
  end
end