serialize using YAML coder

YAML.rb

###
# define serialize in +ActiveRecord::AttributeMethods::Serialization#serialization+
#   => create coder
# which is used in +ActiveRecord::Type::Serialized+
# attr is loaded in +ActiveRecord::Type::Serialized#type_cast_from_database+
# attr is dumped in +ActiveRecord::Type::Serialized#type_cast_for_database+
###

# active_record/coders/yaml.rb
module ActiveRecord::Coders
  class YAML
    def self.dump(obj)
      ::YAML.dump obj
    end

    def self.load(yaml)
      ::YAML.load yaml unless yaml.nil?
    end
  end
end