FileUriUnique.php

<?php

namespace Drupal\file\Plugin\Validation\Constraint;

use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Validation\Attribute\Constraint;
use Drupal\Core\Validation\Plugin\Validation\Constraint\UniqueFieldConstraint;
use Drupal\Core\Validation\Plugin\Validation\Constraint\UniqueFieldValueValidator;

/**
 * Supports validating file URIs.
 */
class FileUriUnique extends UniqueFieldConstraint {
  public function __construct(mixed $options = NULL, ?bool $caseSensitive = NULL, $message = 'The file %value already exists. Enter a unique file URI.', ?array $groups = NULL, mixed $payload = NULL) {
    $this->caseSensitive = $caseSensitive ?? TRUE;
    parent::__construct($options, $caseSensitive, $message, $groups, $payload);
  }
  
  /**
   * {@inheritdoc}
   */
  public function validatedBy() : string {
    return UniqueFieldValueValidator::class;
  }

}