Have you ever wanted to store an array, hash or object in a database column? Using Active Record and YAML makes this completely painless. 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.
You can also specify a class option as the second parameter that‘ll raise an exception if a serialized object is retrieved as a descendant of a class not in the hierarchy.
Nothing new here, but something that can be pretty powerful. Working with people not used to Ruby or ActiveRecord brings back some of the nice “magic” we take for granted on a regular basis. (Samples taken directly from Ruby on Rails API Documentation)
Nice. For DataMapper, I’d do something like this:
class Model
include DataMapper::Resource
property :id, Serial
property :column, Text
before :save do
attribute_set(:column, column.to_yaml) unless column.is_a?(String)
end
def column
@column ||= YAML.load(attribute_get(:column))
end
end
It does make me wonder if there is something similar for DM, though. Also, I’ve not tested the code, it’s proof of concept only. :)
The YAML serializer can be painfully slow… I typically use the same technique but use the JSON serializer since it’s faster (not pure). I usually just override the attribute acessors with my dump/load code (one of these days I will create my own plugin). The fastest technique is to use Marshal but it’s not guaranteed to be forwards compatible.