class AddCustomFieldsPosition < ActiveRecord::Migration def self.up add_column(:custom_fields, :position, :integer, :default => 1) CustomField.find(:all).group_by(&:type).each_value do |fields| fields.each_with_index do |field, i| # do not call model callbacks CustomField.update_all "position = #{i+1}", {:id => field.id} end end end def self.down remove_column :custom_fields, :position end end