title: octobercms backend form - Refresh form after fields change?
body: <p>with builder plugin, I try to validate my form fields.
  I used filterFields() to check fields on the fly.
  Now I want to make some date validation before DB save.
  I used the following code to clear a field like in filterFields().</p>
  
  <pre><code>// Called before the model is validated (bouton SAVE)
  public function beforeValidate() {
      if ($this-&gt;date_begin &gt; $this-&gt;date_end) {
          $this-&gt;attributes['date_end'] = null;      // clear date
      }
  }
  </code></pre>
  
  <p>my problem is that <strong>I would like to refresh the form field or the complete form</strong> to reflect the modifications.
  Would somebody put me on the way to do it ?
  Thanks</p>