J'ai découvert par hasard ceci :

Saving arrays, hashes, and other non-mappable objects in text columns
Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method serialize. This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work. Example:

 class User < ActiveRecord::Base
   serialize :preferences
 end

 user = User.create(:preferences => { "background" => "black", "display" => "large" })

 User.find(user.id).preferences # => { "background" => "black", "display" => "large" }

Une dé/sérialisation de données aussi aisée ? J'aime.