Custom filter query in symfony 1.4

This cracked my head in this wee hour. Thankfully I got it working.

# add the custom field in myapp/modules/client/config/generator.yml
filter:
  display: [ existing_fields, paid_up_cap_more]
  fields: 
    paid_up_cap_more: { label: Paid up capital (RM) - more than }

// in lib/filter/doctrine
class CrmClientFormFilter extends BaseCrmClientFormFilter
{
  public function configure() {
    $this->widgetSchema['paid_up_cap_more'] =  new sfWidgetFormInput();
    $this->validatorSchema['paid_up_cap_more'] = new  sfValidatorPass(array ('required' => false));
  }
  
  public function getFields() {
    $fields = parent::getFields();
    $fields['paid_up_cap_more'] = 'paid_up_cap_more';
    return $fields;
  }

  // must be in this format addXXXXXColumnQuery
  protected function addPaidUpCapMoreColumnQuery($q, $element, $value) {
    if (!empty($value)){
         $q->andWhere('paid_up_capital >= ?', $value);
         return $q;
    }
  }
}