title: How to get only changed value on Firebase Database?
body: <p>How to get only changed value on Firebase Database? Because every time I changed a value on <code>dir</code>, ex: </p>
  
  <pre><code>/ some_user
   ~ id
   ~ name
   / data
     ~ order_id
     ~ order_name &lt;&lt;= Changed in here
  </code></pre>
  
  <p>But when I get the changed data, I get all the tree structure and not only changed data <code>order_name</code>. So I just wanted it to return something like this:</p>
  
  <pre><code>/ some_user
       / data
         ~ order_name &lt;&lt;= Specific changed data
  </code></pre>
  
  <p>So I can identify what is the exact <code>key</code> data that has changed. How can I do this? Thanks.</p>