os2web_postlister.module

<?php

use Drupal\node\NodeInterface;

/**
 * Implements hook_entity_presave().
 *
 * On a new node save copies header from title if header value is empty.
 */
function os2web_postlister_node_presave(NodeInterface $node) {
  if ($node->isNew() && $node->getType() == 'os2web_postlister') {
    // If header is empty, use the title.
    if (empty($node->field_os2web_postlister_heading->value)) {
      $node->field_os2web_postlister_heading->value = $node->label();
    }
  }
}