application_helper.rb

  FLASH_NOTICE_KEYS = [:error, :notice, :warning, :message, :success]

  def flash_messages
    return unless messages = flash.keys.select{|k| FLASH_NOTICE_KEYS.include?(k)}
    formatted_messages = messages.map do |type|
      content_tag :div, :class => "#{type}Explanation" do
        flash_message_for(flash[type])
      end
    end
    formatted_messages.join
  end

  def flash_message_for(message)
    if message.is_a?(Array)
      flash_message_for_array(message)
    elsif message.is_a?(Hash)
      flash_message_for_hash(message)
    else
      content_tag :p, message
    end
  end

  def flash_message_for_array(messages)
    formatted_messages = messages.map { |msg| content_tag(:li, msg) }
    content_tag :ul, formatted_messages.join
  end

  def flash_message_for_hash(message)
    [content_tag(:h2, message[:title]), flash_message_for(message[:body])].join
  end