Validation and Constraints
Traditionally, validation in Silverstripe CMS has been mostly handled through form validation.
While this is a useful approach, it can lead to data inconsistencies if the record is modified outside of the form context.
Most validation constraints are actually data constraints which belong on the model. Silverstripe CMS provides the
DataObject::validate() method for this purpose. The validate() method is
called any time the write() method is called, before the onBeforeWrite() extension hook.
By default, there is no validation - objects are always valid! However, you can override this method in your DataObject
sub-classes to specify custom validation, or use the validate() extension hook through an Extension.
Invalid objects won't be able to be written - a ValidationException will be thrown and no write will occur.
Ideally you should call validate() in your own application to test that an object is valid before attempting a
write, and respond appropriately if it isn't.
The return value of validate() is a ValidationResult object.
use SilverStripe\ORM\DataObject;
class MyObject extends DataObject
{
private static $db = [
'Country' => 'Varchar',
'Postcode' => 'Varchar'
];
public function validate()
{
$result = parent::validate();
if($this->Country == 'DE' && $this->Postcode && strlen($this->Postcode) != 5) {
$result->addError('Need five digits for German postcodes');
}
return $result;
}
}