gistfile1.txt

  protected function _serializeField(DataObject $object, $field, $defaultValue = null, $unsetEmpty = false)
    {
        $value = $object->getData($field);
        if (empty($value) && $unsetEmpty) {
            $object->unsetData($field);
        } else {
            if (is_string($value)) {
                $object->setData($field, $value ?: $defaultValue);
            } else {
                $object->setData($field, serialize($value ?: $defaultValue));
            }
        }

        return $this;
    }