decode json deserialize rails model with relationships

gistfile1.rb

class User < ActiveRecord::Base
belongs_to :address

accepts_nested_attributes_for :address #Para permitir usar address_attributes 

 def to_custom_json
    hash = self.to_json(:include => :address, :except => [:address_id, :address_id])
    hash.sub("address", "address_attributes")
  end
end

#Exemplo de como serializar e deserializar:
user = User.new
user_json = user.to_custom_json
user2 = User.new(ActiveSupport::JSON.decode(user_json))