acts_as_json_store.rb

module ActsAsJSONStore
  def self.included base 
    base.extend ClassMethods
  end

  module ClassMethods
    attr_reader :fields_acting_as_json_store

    # Declare a list of attributes in a model to act as JSON store.
    # @param [Symbol, ...] The list of attributes.
    def acts_as_json_store *attributes
      (((@fields_acting_as_json_store ||= []) << attributes).flatten!).uniq!
      attributes.each do |column|
        define_method column do
          JSON.parse(self[column]) rescue self[column]
        end

        define_method :"#{column}=" do |value|
          self[column] = value.kind_of?(Enumerable) ? value.to_json : value
        end
      end
    end
  end
end

ActiveRecord::Base.send(:include, ActsAsJSONStore)