how do you solve this

circular_json.rb

#!/usr/bin/env ruby
require 'mongo'
require 'bson'
require 'json'

class Datastore
	@db = nil
	def initialize (database)
		@dbname = database
	end

	def get_object(type, id)
		{:id => id}
	end

	def get_object_list(type,spec = {})
		Hash.new(:info => Hash.new )
	end

	def create_object(type)
		{}
	end

	def update_object(type, object_hash, keys = [])
		{}
	end

end

class MongoDatastore < Datastore

	def get_object(type, id)
		@db.collection(type).find_one(:_id =>id).
	end

	def get_object_list(type,spec = {} )
		@db.collection(type).find(spec)
	end

	def create_object(type)
		get_object(type,@db.collection(type).insert({}))
	end

	def update_object(type,object_hash,keys = [:_id] )
		
		search_hash = {}
		keys.each { |key| 
			{key => object_hash[key]} if object_hash[key]
      puts key, object_hash[key]
		}
		object_hash = @db.collection(type).update(search_hash,object_hash)
		create_object(type).merge!(object_hash) unless object_hash[:_id]

	end

  def initialize(database)
    super(database)
    @db = Mongo::Connection.new.db(@dbname)
  end

end

end

class User < Hash

	def initialize(uniq_id)
		self[:uniq_id] = uniq_id
	end

	def attend_event(event)
		self[:attending] = event
	end

end

class Event < Hash

	def initialize (user)
		self[:creator] = user
		user.attend_event(self)
	end


end


bob = User.new('bob@email.com')
myfavoritesportsteam = Event.new(bob)


store = MongoDatastore.new('play')
store.update_object('user',bob)
store.update_object('event',myfavoritesportsteam)
puts "After Store"
puts bob.to_json, myfavoritesportsteam.to_json

puts store.get_object_list('user').to_json
puts store.get_object_list('event').to_json