I'm a Drupal8 newbie. I installed a third party module simplelogin, and I attempted to change the {{site_name}} value in page--simplelogin.html.twig but can not find a right way.

I noticed that the variable is defined in simplelogin.module:

function simplelogin_preprocess_simplelogin(&$variables) {
  $path = \Drupal::service('path.current')->getPath();
  $module_path = drupal_get_path('module', 'simplelogin');

  $variables['#attached']['library'][] = 'simplelogin/simplelogin-library';

  // Able to use custom variables
  $variables['path'] = $path;
  $variables['base_path'] = base_path();
  $variables['logo'] = file_url_transform_relative(file_create_url(theme_get_setting('logo.url')));
  $variables['background_class'] = simple_login_settings('active');
  $variables['background_opacity'] = simple_login_settings('opacity');
  $variables['wrapper_width'] = simple_login_settings('width');
  $variables['site_name'] = \Drupal::config('system.site')->get('name');
  $variables['site_register'] = \Drupal::config('user.settings')->get('register');

I guess the second "simplelogin" presented in the hook function is a form element in the theme (I'm not quite clear although), as I found $form['simplelogin'] appears in the buildForm function of form controller.

  public function buildForm(array $form, FormStateInterface $form_state, Request $request = NULL) {


    $simplelogin_config = $this->config('simplelogin.settings');

    $imageid = $simplelogin_config->get('background_image');
    if ($imageid) {
      $file = \Drupal\file\Entity\File::load($imageid[0]);  // File Load 
      $fileUrl = $file->getFileUri();

      // check if image is valid.
      $image = \Drupal::service('image.factory')->get($fileUrl);
      if ($image->isValid()) {
        $image_render = array(
          '#theme' => 'image_style',
          '#width' => $image->getWidth(),
          '#height' => $image->getHeight(),
          '#style_name' => 'medium',
          '#uri' => $fileUrl,
    //$renderer = \Drupal::service('renderer');
    //$renderer->addCacheableDependency($image_render, $file);

    $form['simplelogin'] = array(
      '#type'            => 'details',
      '#title'           => $this->t('Configuration'),
      '#open'            => TRUE,

      'background_active' => array(

1. created a custom module named "mylogin", this is the info.yml:

name: myLogin
description: my login module
type: module

version: '8.x-1.0'
package: 8.x
core: '8.x'
project: 'mylogin'

  - simplelogin

2. override hook_preprocess_page in mylogin.module:

use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Url;
use Drupal\file\Entity\File;
use Drupal\Core\Controller\ControllerBase;
use Drupal\simplelogin\Controller;

function mylogin_preprocess_page(&$variables) {
  if (\Drupal::routeMatch()->getRouteName() == 'user.login') {
    $variables['site_name']= 'test';

But it cannot work, and I believe the preprocess is not triggered. Is there a simple way to override the needed variable while keep the others in the module's preprocess function? Any help will be very appreciated.

1 Answer 1


You can create a new module use hook_theme_registry_alter like module simplelogin like this:

 * Implements hook_theme_registry_alter
 * {@inheritdoc}
function YOUR_MODULE_theme_registry_alter(&$theme_registry) {
  $theme_registry['page__simplelogin'][preprocess functions] = [
    0 => 'simplelogin_preprocess_simplelogin',
    1 => 'YOUR_MODULE_preprocess_function'
  • I tried this, but it still not triggered the preprocess function...
    – richardson
    Commented Jan 8, 2019 at 8:50
  • Did you try clear cache? If doesn' working try create module start with string t (u, v .. string after S).
    – Jonh
    Commented Jan 8, 2019 at 9:00
  • Yes, I did clear cache. What do you mean by "create module start with string...", rename the module?
    – richardson
    Commented Jan 8, 2019 at 9:13
  • Yes, the list hooks is array. I guess this array order by module name. So may be your hook run before simplelogin's hook.
    – Jonh
    Commented Jan 8, 2019 at 9:19
  • Do I need to declare the function path somewhere? The two functions locate in different place.
    – richardson
    Commented Jan 8, 2019 at 9:21

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