pklingem

class AddCountOnHandToVariantsAndProducts < ActiveRecord::Migration
  def self.up
    add_column :variants, :count_on_hand, :integer, :default => 0, :null => false
    add_column :products, :count_on_hand, :integer, :default => 0, :null => false

    Variant.class_eval do
      def on_hand=(new_level)
        delta_units = new_level.to_i - on_hand.to_i

        # increase Inventory when positive delta

pklingem

module ActiveRecord
  module NestedAttributes #:nodoc:
    module ClassMethods
      # Defines an attributes writer for the specified association(s). If you
      # are using <tt>attr_protected</tt> or <tt>attr_accessible</tt>, then you
      # will need to add the attribute writer to the allowed list.
      #
      # Supported options:
      # [:allow_destroy]
      #   If true, destroys any members from the attributes hash with a