Introduce events and deprecate hooks

@SomebodySysop, I'm reading this and seeing your example, I'm backing the idea to put in some examples on the module.

The reason your code isn't working, is because:

return [
   'SearchApiSolrEvents::POST_EXTRACT_RESULTS' => 'processResults'
];

Must return an array like: Class => 'function'. You are returning a 'string' => 'string', which isn't working.

I had to use an PostFieldMappingEvent and did it like so:

services.yml file:

services:
  custom_module.event_subscriber:
    class: Drupal\custom_module\EventSubscriber\PostFieldMappingEvent
    tags:
      - { name: event_subscriber }

My PostFieldMappingEvent.php file:

namespace Drupal\custom_module\EventSubscriber;

use Drupal\search_api_solr\Event\SearchApiSolrEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Custom module event subscriber.
 */
class PostFieldMappingEvent implements EventSubscriberInterface {

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents(): array {
    return [
      SearchApiSolrEvents::POST_FIELD_MAPPING => 'alterSolrFieldNames',
    ];
  }

  /**
   * Change the Solr field names.
   *
   * @param \Drupal\search_api_solr\Event\PostFieldMappingEvent $event
   */
  public function alterSolrFieldNames(PostFieldMappingEvent $event): void {
    // Your code here
  }

}

I hope this makes it easier to understand, but maybe we still need to add some examples. Not everyone knows how to use Events..

Thank you very much for the reply. I get the example you provided. The problem is, now knowing much about events, I followed the global examples I saw. Which is really why it is so useful to have search api solr examples available *somewhere*.

I've added a guide page explaining how to replace the deprecated hook_search_api_solr_query_alter with PreQueryEvent. Hopefully it helps some people.
https://www.drupal.org/docs/8/modules/search-api-solr/search-api-solr-ho... →

@nicrodgers Thanks very much for the guide page, this has been very helpful. Since the changes here were released in search_api_solr 4.2.4, maybe the guide should mention updating your dependencies to require >= 4.2.4, or even ^4.3? I suppose this is more relevant to other contrib modules that have been using the hooks.

@nicrodgers Thank you so much for the documentation page. It really helps me to replace the deprecated hook_search_api_solr_documents_alter with PostCreateIndexDocumentsEvent.

Just came across this in my case I was trying to add an extra field as I used to do in hook_search_api_solr_documents_alter()

See search_api_solr/src/Event/PostCreateIndexDocumentsEvent.php for doc
but here is the quick version

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents(): array {
    return [
      SearchApiSolrEvents::POST_CREATE_INDEX_DOCUMENTS => 'alterSolrFieldsAfterIndex',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function alterSolrFieldsAfterIndex(PostCreateIndexDocumentsEvent $event): void {
    $documents = $event->getSolariumDocuments();
    foreach ($documents as $document) {
      $documentFields = $document->getFields();
      .... 
      $document->setField('ss_test', 'hello');
    }
    $event->setSolariumDocuments($documents);
  }