title: What's the best way to check if an active record object has just been created?
body: <p>Specifically I want to check that the record has been created in the database, but there haven't been any subsequent updates.</p>
  
  <p>Up until now I've been checking that the <code>updated_at</code> and <code>created_at</code> are the same, but I've found that depending on the amount of work required to create the model, these can sometimes differ by a few milliseconds.</p>
  
  <p>Right now I'm using <code>if self.changed? &amp;&amp; self.id_changed?</code>, as the only time the <code>id</code> will change will be when the object is first saved. This works fine, but I'm curious to see if there's a more well established way of doing this.</p>