Change out of dated README.md file

Hi, I think the problem is mainly, that a keyvalue is needed to be saved on the backend possibly for security reasons.

$key_value_storage = \Drupal::service('keyvalue')->get('entity_autocomplete');
if (!$key_value_storage->has($selection_settings_key)) {
  $key_value_storage->set($selection_settings_key, $selection_settings);
}

And a the url should be generated this way:

$url = Drupal\core\Url::fromRoute(
  'autocomplete_deluxe.autocomplete',
  $route_parameters,
  ['absolute' => TRUE]
  )->getInternalPath();

With these modifications it worked for me.

As of Drupal 11.1.7 and Autocomplete Deluxe 2.1.2, the previous code no longer works. Here is an updated version that is working for me. I can create a patch for the readme file is the maintainer is interested:

use Drupal\Component\Utility\Crypt;
use Drupal\Core\Site\Settings;

/**
 * Implements hook_form_alter().
 */
function your_module_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  if ($form_id == 'views_exposed_form') {
    // Add a call for each exposed filter you want to alter, using the field's machine name.
    your_module_autocomplete_deluxe_filter('field_tags', $form);
    your_module_autocomplete_deluxe_filter('field_categories', $form);
  }
}

/**
 * Converts the exposed filter of a field into an autocomplete deluxe widget.
 *
 * @param string $field_name
 *   Name of the field included as exposed filter in the form.
 * @param array $form
 *   Instance of the form array.
 */
function your_module_autocomplete_deluxe_filter(string $field_name, array &$form) {
  $filter_id = $form['#info']['filter-' . $field_name . '_target_id']['value'] ?? FALSE;

  if (!isset($form[$filter_id])) {
    return;
  }

  $selection_settings = [
    'target_bundles' => $form[$filter_id]['#selection_settings']['target_bundles'],
    'sort' => ['field' => '_none'],
    'auto_create' => FALSE,
    // Even though we've specified '0' for 'auto_create', it seems that
    // a value for 'auto_crteate_bundle' is required for this to work.
    'auto_create_bundle' => 'tags',
    'match_operator' => 'CONTAINS',
  ];

  $target_type = $form[$filter_id]['#target_type'];
  $selection_handler = 'default:taxonomy_term';
  $data = serialize($selection_settings) . $target_type . $selection_handler;

  $selection_settings_key = Crypt::hmacBase64($data, Settings::getHashSalt());

  $key_value_storage = \Drupal::service('keyvalue')->get('entity_autocomplete');
  if (!$key_value_storage->has($selection_settings_key)) {
    $key_value_storage->set($selection_settings_key, $selection_settings);
  }

  $route_parameters = [
    'target_type' => $target_type,
    'selection_handler' => $selection_handler,
    'selection_settings_key' => $selection_settings_key,
  ];

  $url = \Drupal::urlGenerator()->getPathFromRoute('autocomplete_deluxe.autocomplete', $route_parameters);

  $form[$filter_id] = [
    '#type' => 'autocomplete_deluxe',
    '#autocomplete_deluxe_path' => $url,
    '#selection_settings' => $selection_settings,
    '#multiple' => TRUE,
    '#target_type' => $target_type,
    '#selection_handler' => $selection_handler,
    '#limit' => 10,
    '#size' => 60,
    '#new_terms' => 0,
    '#min_length' => 0,
    '#delimiter' => ',',
    '#not_found_message_allow' => 0,
    '#not_found_message' => "The term '@term' will be added.",
    '#cardinality' => -1,
  ];
}