memoize.rb

require 'bundler/setup'
require 'mongo_mapper'

MongoMapper.connection = Mongo::Connection.new("127.0.0.1", 27017, 
  :logger => Logger.new(STDOUT))
MongoMapper.database = 'tmp'

class Example
  include MongoMapper::Document
  
  key :name, String, :unique => true
  
  def self.find_by_name(name)
    first(:name => name)
  end
  
  # Allows Memoizable to handle class-methods
  class << self
    extend ActiveSupport::Memoizable
    memoize :find_by_name
  end
end

Example.collection.drop
Example.create(:name => 'foo')
Example.create(:name => 'bar')

puts "-- MEMOIZE"
puts " - first call:"
Example.find_by_name('foo')
Example.find_by_name('bar')
puts " - second call:"
Example.find_by_name('foo')
Example.find_by_name('bar')


puts "\n-- WITH RELOAD ARG"
puts " - first call:"
Example.find_by_name('foo', :reload)
Example.find_by_name('bar', :reload)
puts " - second call:"
Example.find_by_name('foo')
Example.find_by_name('bar')


puts "\n-- FLUSH CACHE"
Example.flush_cache(:find_by_name)
puts " - first call:"
Example.find_by_name('foo')
Example.find_by_name('bar')
puts "   second call:"
Example.find_by_name('foo')
Example.find_by_name('bar')