vanilla ruby class with list of activerecord objects integrates with rails form helpers

gistfile1.rb

#I want to create many of a thing in one shot where thing is an activerecord class with 
#validations.  I can use the following where a listofthings is a vanilla ruby class. on 
#valid?  this class calls all the contained object's valid? method.  and a naive save that 
#calls save on each of the contained activerecord objects.  There's some syntatic sugar, 
#methods that hide the underlying list.  This is minimal code for explanation.  
 
#My thing is an activerecord class
#ListOfMyThings is a vanilla ruby class
#thing to note for form helpers to work you need
# _attributes=(attributes) method defined.

class MyThingValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    value.each do |val|
      record.errors[attribute] << val.errors unless val.valid?
    end
  end
end

class ListOfMyThings
  include ActiveModel::Validations
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  #include Enumerable
  attr_accessor :my_things
  validates :my_things, :my_thing => true  
  def initialize(my_things = [])
    self.my_things = [my_things].flatten
  end
  
  #convenience methods
  def <<(val)
    my_things << val
  end
  
  def [](i)
    my_things[i]
  end
  
  # def each
  #   my_things.each do |c|
  #     yield c
  #   end
  # end
  
  def persisted?
    false
  end
  
  def save
    if valid?
      my_things.each do |my_thing|
        my_thing.save
      end
    end
  end
  
  def my_things_attributes=(attributes)
    #logger.warn(attributes.inspect)
  end