Add a search api processor for view unpublished

Problem

There is an open discussion about how search api handles access. One of the reported problems is that it does not work view_unpublished. The content access search api processor does not respect view_unpublished permissions and if a user with view unpublished content permission is unable to view unpublished nodes/content in the search result.In the discussion the module maintainer suggest that other modules build their own. https://www.drupal.org/project/search_api/issues/1617794 →

Proposed Solution

Add a search_api plugin that allow for choosing a processor that supports view_unpublished. (See screenshot).In this processor we check for appropriate permissions.

Usage

1. Apply patch
2. Make sure search api enabled
3. go to admin/config/search/search-api/index/default_index/processors
4. Check the box Content Access: View unpublished. Also ensure the Content Access is not checked (see screen shot below)

Patch attached below. It reuse the same addNodeAccess method defined by ContentAcess in the search_api module but removed the code where unpublished content is filtered out namely:

    // Collect all the required fields that need to be part of the index.
    $unpublished_own = $account->hasPermission('view own unpublished content');

    $enabled_conditions = $query->createConditionGroup('OR', ['content_access_enabled']);
    foreach ($affected_datasources as $entity_type => $datasources) {
      foreach ($datasources as $datasource_id) {
        // If this is a comment datasource, or users cannot view their own
        // unpublished nodes, a simple filter on "status" is enough. Otherwise,
        // it's a bit more complicated.
        $status_field = $this->findField($datasource_id, 'status', 'boolean');
        if ($status_field) {
          $enabled_conditions->addCondition($status_field->getFieldIdentifier(), TRUE);
        }
        if ($entity_type == 'node' && $unpublished_own) {
          $author_field = $this->findField($datasource_id, 'uid', 'integer');
          if ($author_field) {
            $enabled_conditions->addCondition($author_field->getFieldIdentifier(), $account->id());
          }
        }
      }
    }
    $access_conditions->addConditionGroup($enabled_conditions);