admin_helper.rb

  def change_history(audits)
    result = ''
    unless audits.nil? || audits.empty?
      result << '<h1>Change history</h1>'
      audits.each do |audit|
        result << "<p><b>Version #{audit.version} (#{audit.action.titleize}, #{audit.created_at.in_time_zone('America/Denver').to_s(:long)}):</b><br />"
        result << '<ul>'
        audit.changes.each do |attribute, delta|
          if delta.is_a?(Array)
            result << "<li>Changed #{attribute.titleize}: from '#{delta.first}' to '#{delta.last}'</li>"
          else
            result << "<li>Set #{attribute.titleize} to '#{delta}'</li>"
          end
        end
        result << '</ul>'
      end
      result << '</p>'
    end
  end