WP Core: Where are terms populated for the admin edit screen?

Question

I am trying to understand how the Admin Tables are populated (for posts, users, plugins...).

With Terms/Taxonomies I am confused. In the /wp-admin/edit-tags.php file everything is normal until we reach the $wp_list_table->prepare_items() method (where an $args is set up to later on go fetch data), but from there on I don't understand where the actual database query takes place.

Looking at the WP Users List Table's prepare_items() method, it's quite clear:

$wp_user_search = new WP_User_Query($args);
$this->items = $wp_user_search->get_results();

So I expected a similar approach for Terms, but looking at the WP Terms List Table class, you can find:

public function has_items(){
    // todo: populate $this->items in prepare_items()
    return true;
}

Which means that the items are loaded somewhere else. But where?

Answer 1

The items are loaded via get_terms() (see source on Trac) in the display_rows_or_placeholder() method which is called in the display() method which is called in wp-admin/edit-tags.php (see source on Trac). But the $items property is never populated with the terms.