/Drupal 8

function hook_file_validate

hook_file_validate(Drupal\file\FileInterface $file)

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.


\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


Related topics

Define functions that alter the behavior of Drupal core.


core/modules/file/file.api.php, line 27
Hooks for file module.


function hook_file_validate(Drupal\file\FileInterface $file) {
  $errors = array();

  if (!$file->getFilename()) {
    $errors[] = t("The file's name is empty. Please give a name to the file.");
  if (strlen($file->getFilename()) > 255) {
    $errors[] = t("The file's name exceeds the 255 characters limit. Please rename the file and try again.");

  return $errors;

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