Check that files meet a given criteria.

This hook lets modules perform additional validation on files. They're able to report a failure by returning one or more error messages.

Parameters

\Drupal\file\FileInterface $file: The file entity being validated.

Return value

array An array of error messages. If there are no problems with the file return an empty array.

See also

https://www.drupal.org/node/3363700

\Drupal\file\Validation\FileValidatorInterface

Related topics

File

core/modules/file/file.api.php, line 81

Code

function hook_file_validate(\Drupal\file\FileInterface $file) {
  $errors = [];
  if (!$file->getFilename()) {
    $errors[] = t("The file's name is empty. Give a name to the file.");
  }
  if (strlen($file->getFilename()) > 255) {
    $errors[] = t("The file's name exceeds the 255 characters limit. Rename the file and try again.");
  }
  return $errors;
}

---