This gem supplies an YAMLColumn coder that returns nil instead of a blank object. Useful when the class you are serializing to/from does not allow uninitialized objects (such as a unit measurement)

Suppose you have this:

class Sandwich < ActiveRecord::Base
  attr_accessible :length
  serialize :length, Unit
end

This happens:

2.0.0-p247 :002 > Sandwich.new
ArgumentError: Invalid Unit Format

Because ActiveRecord is trying to do this:

2.0.0-p247 :003 > Unit.new
ArgumentError: Invalid Unit Format

So in config/initializers/ruby-units.rb

Unit.instance_eval do
  include NilReturningCoder
end

Now your shit works

2.0.0-p247 :002 > Sandwich.new
 => #<Sandwich id: nil, length: nil>