class AddEnumerationsPosition < ActiveRecord::Migration def self.up add_column(:enumerations, :position, :integer, :default => 1) unless Enumeration.column_names.include?('position') Enumeration.find(:all).group_by(&:opt).each do |opt, enums| enums.each_with_index do |enum, i| # do not call model callbacks Enumeration.update_all "position = #{i+1}", {:id => enum.id} end end end def self.down remove_column :enumerations, :position end end