How to make file description field as required?

Question

I would like to set the file description as required. I tried it with this code:

function mymodule_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {

  if ($form_id == 'node_news_homepage_edit_form') {

    $form['field_downloads']['widget'][0]['description_field']['#required'] = TRUE;
  }
}

But it didn't work. Could anyone help me?

Answer 1

The community is working to solve this problem: https://www.drupal.org/project/drupal/issues/2320877

While this isn't the part of the Drupal core, you can do the following:

function mymodule_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  if ($form_id == 'node_news_homepage_edit_form') {
    $form['field_downloads']['widget'][0]['#process'][] = 'set_file_description_required';
  }
}

function set_file_description_required($element) {
    $element['description']['#required'] = TRUE;
    return $element;
}

Answer 2

Based on @DavidCzinege answer, a version that works for any form where the field appears and also for multivalued fields:

use Drupal\Core\Render\Element;

/**
 * Implements hook_form_alter().
 */
function my_module_form_alter(&$form, &$form_state, $form_id) {

  if (!empty($form['field_file']['widget'])) {

    foreach (Element::children($form['field_file']['widget']) as $el_index) {

      $form['field_file']['widget'][$el_index]['#process'][] = 'my_module_set_file_description_required';

  }

}

function my_module_set_file_description_required($element) {

  $element['description']['#required'] = TRUE;
  return $element;

};