title: parent child relationship self join
body: <p>My <code>Event</code> model needs to have a self-referential join. Every event can belong to one other event. So there is <strong>one</strong> parent. An event can not belong to any other parents.</p>
  
  <p>I read <a href="http://guides.rubyonrails.org/association_basics.html#self-joins" rel="nofollow">the AR docs</a> on the subject, but for some reason keep getting stumped on what relation I should use in my model.</p>
  
  <p>Any suggestions on what relation to use?</p>