title: using touch() to update timestamp of custom timestamp field in laravel
body: <p>Is there a way to use <code>touch()</code> for updating timestamp of <code>is_online</code> field in table instead of updating <code>created_at</code> field in <strong>laravel</strong> <code>Eloquent ORM</code></p>
  
  <p>At present I am using</p>
  
  <pre><code>User::where('id',$senderId )-&gt;update(array('is_online' =&gt; date('Y-m-d H:i:s')));
  </code></pre>