forms

Writing this post down as a note to self about using sfValidatorCallback.
Step 1: add the sfValidatorCallback to the widget

public function configure()
{
$this->widgetSchema['my_field'] =
new sfWidgetFormTextArea(array(‘required’ => false));
// add the validator
$this->validatorSchema['my_field'] = new sfValidatorCallback(
array(‘callback’ => array(
[...]