messages_controller.rb

  def interested_in_reply
    @message = Message.find_by_id(params[:id])
    sender_email = User.find_by_id(@message.sender_id).profile.email
    desc = @message.automatic_description_for_all_types(@message.post_type,@message.post_id)
    if @message.is_interested==false
      @message.is_interested=1
      @message.save
      Mailer.deliver_interested_reply_to_mail(sender_email, @message, desc)
      render  :nothing => true, :text => "You have replied that you have interest in his #{@message.post_type}.",:layout =>"main"
    else
      render  :nothing => true
    end
  end