[site-reviews] sort posts by rank with Elementor Pro

/**
 * This will sort posts added to your page with the Elementor Posts widget by
 * rank, assuming that you are assigning reviews to the post_type chosen in the
 * "Query > Source" option of the widget. In order for this to work, you will also
 * need to set the "Query > Query ID" option of the widget to: "sort-by-rank".
 *
 * If you would prefer to sort by rating instead of rank,
 * replace "_glsr_ranking" with "_glsr_average" in the function.
 *
 * @param \WP_Query $query
 * @return void
 */
add_action('elementor/query/sort-by-rank', function ($query) {
    $query->set('meta_query', [
        'relation' => 'OR',
        ['key' => '_glsr_ranking', 'compare' => 'NOT EXISTS'], // this comes first!
        ['key' => '_glsr_ranking', 'compare' => 'EXISTS'],
    ]);
    $query->set('orderby', 'meta_value_num');
});