ConfigExistsConstraint.php

<?php

declare (strict_types=1);
namespace Drupal\Core\Config\Plugin\Validation\Constraint;

use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Validation\Attribute\Constraint;
use Symfony\Component\Validator\Constraint as SymfonyConstraint;

/**
 * Checks that the value is the name of an existing config object.
 */
class ConfigExistsConstraint extends SymfonyConstraint {
  
  /**
   * Constructs a ConfigExistsConstraint object.
   *
   * @param string $prefix
   *   Optional prefix, to be specified when this contains a config entity ID.
   *   Every config entity type can have multiple instances, all with unique IDs
   *   but the same config prefix. When config refers to a config entity,
   *   typically only the ID is stored, not the prefix.
   * @param string $message
   *   The error message if the config does not exist.
   * @param array|null $groups
   *   The groups that the constraint belongs to.
   * @param mixed|null $payload
   *   Domain-specific data attached to a constraint.
   */
  public function __construct(public string $prefix = '', public string $message = "The '@name' config does not exist.", ?array $groups = NULL, mixed $payload = NULL) {
    parent::__construct(groups: $groups, payload: $payload);
  }

}