How to update table taxonomy_index when adding a node referencing a term?

Question

I have two node types: Lesson and Exercise. A lesson contains several exercises, which are children. Lessons have a category field which is a reference field of type taxonomy term. Exercises point to lessons through a Lesson reference field, which I suppose indirectly maps exercises to terms.

When I create a lesson, I use the following code:

    $node = Node::create([
      // The node entity bundle.
      'type' => 'lesson',
      'langcode' => 'en',
      'created' => $lesson->created,
      'changed' => $lesson->changed,
      'uid' => $lesson->uid,
      'title' => $lesson->title,
      'field_category' => $tid,
      'body' => [
        'summary' => $lesson->summary,
        'value' => $lesson->body,
        'format' => 'full_html',
      ],
    ]);
    $node->save(); 

Note the field_category field.

The above does not result in the taxonomy_index table being updated. I could update it with an sql query, but I would like to know how to do it via the above core approach.

And for the Exercise node type, I suppose I need to do likewise, unless my linking of an Exercise to a Lesson already accomplishes the hierarchy.

How do I alter the above to result in the taxonomy_index table being updated?

Answer 1

I ended up figuring this out. here is what I did:

$result=db_query("SELECT nid FROM node WHERE type = 'lesson'");
foreach($result as $row){
    $node=entity_load('node', $row->nid);
    $result =  taxonomy_build_node_index($node);
}

This ensures that my lesson node is tracked in the taxonomy_index table. I should probably start learning the class-based approach, but for now this works.