Validation and constraints#

Validation using symfony/validator constraints#

The ConstraintValidator class provides an abstraction around symfony/validator, so you can easily validate values against symfony's validation constraints and get a ValidationResult object with the result.

use SilverStripe\Core\Validation\ConstraintValidator;

/**
 * @var \Symfony\Component\Validator\Constraint $constraint
 * @var \SilverStripe\ORM\ValidationResult $result
 */
$result = ConstraintValidator::validate($valueToValidate, $constraint);

For example, to test if a URL is valid:

use SilverStripe\Core\Validation\ConstraintValidator;
use Symfony\Component\Validator\Constraints\Url;

$isValid = ConstraintValidator::validate($url, new Url())->isValid();

You can use most of the constraints listed in Symfony's supported constraints documentation, though note that some of them require additional symfony dependencies.

Validation using constraints that rely on symfony/doctrine is explicitly not supported in Silverstripe CMS.

Model validation#

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.

namespace App\Model;

use SilverStripe\ORM\DataObject;

class MyObject extends DataObject
{
    private static $db = [
        'Country' => 'Varchar',
        'Postcode' => 'Varchar',
    ];

    public function validate()
    {
        $result = parent::validate();

        // This will add a field specific error to the ValidationResult
        if (strlen($this->Postcode) > 10) {
            $result->addFieldError('Postcode', 'Postcode is too long');
        }

        // This will add a general error to the ValidationResult
        if ($this->Country == 'DE' && $this->Postcode && strlen($this->Postcode) !== 5) {
            $result->addError('Need five digits for German postcodes');
        }

        return $result;
    }
}

API documentation#

• DataObject
• ValidationResult;