title: Track changes when updating a record
body: <p>How do I check if the data is changed when I edit a record?</p>
  
  <p>So before update</p>
  
  <pre><code>game.player=1
  </code></pre>
  
  <p>after update / edit</p>
  
  <pre><code>game.player=2
  </code></pre>
  
  <p>for example</p>
  
  <p>how to track changes (check if changed) and do something in ruby on rails, when the data is changed.</p>