navigation404.module in 404 Navigation 8

main module file.

File

navigation404.module

<?php

/**
 * @file main module file.
 */
define('NAVIGATION404_PAGE', 'navigation404');
use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_alter().
 */
function navigation404_form_system_site_information_settings_alter(&$form, FormStateInterface $form_state) {

  // Since we don't care what site_404 is set to, let the user set it if they want.
  if ($form['error_page']['site_404']['#default_value'] == NAVIGATION404_PAGE) {
    $form['error_page']['site_404']['#default_value'] = '';
  }

  // Insert our submit handler first.
  array_unshift($form['#submit'], 'navigation404_site_404_submit');
}

/**
 * Submit callback for system_site_information_settings form.
 */
function navigation404_site_404_submit($form, FormStateInterface $form_state) {

  // Make sure site_404 is not empty.
  $site_404 = $form_state
    ->getValue('site_404');
  if (empty($site_404)) {
    $form_state
      ->setValue('site_404', NAVIGATION404_PAGE);
  }
}

Functions

Name	Description
navigation404_form_system_site_information_settings_alter	Implements hook_form_alter().
navigation404_site_404_submit	Submit callback for system_site_information_settings form.

Constants

Name	Description
NAVIGATION404_PAGE	@file main module file.