serializable_attributes.rb

module SerializableAttributes
  extend ActiveSupport::Concern

  included do
    class << self
      attr_reader :serializable_column
    end

    before_save :update_serializable_column

    def self.serialize_attributes(serializable_column = :data)
      @serializable_column = serializable_column
      yield if block_given?
    end

    def self.string(*args)
      args.each { |attr| create_reader(attr) }
      args.each { |attr| create_writer(attr) }
    end

    # Creates the following method:
    #
    #   def favorite_color
    #     store['favorite_color']
    #   end
    #
    def self.create_reader(attribute)
      define_method(attribute) do
        store[attribute.to_s]
      end
    end

    # Creates the following method:
    #
    #   def favorite_color=(favorite_color)
    #     store['favorite_color'] = favorite_color
    #   end
    #
    def self.create_writer(attribute)
      define_method("#{attribute}=") do |value|
        store[attribute.to_s] = value
      end
    end
  end

  private

  def update_serializable_column
    send("#{self.class.serializable_column}=", store.to_json)
  end

  def store
    @store ||= JSON.parse(send(self.class.serializable_column) || "{}")
  end
end

user.rb

class User < ActiveRecord::Base
  include SerializableAttributes

  serialize_attributes do
    string :title, :description
  end
end