WordPress: Reverse ACF query example

advanced-custom-fields.php

/**
 * Example: Reverse ACF query
 */
function dt_get_related_sport_icon_positive($post)
{

    $related_sport_icon_positive = null;

    $sports_term_objects = get_the_terms($post, 'sport_category');

    $sports_term_id = ($sports_term_objects)
        ? $sports_term_objects[0]->term_id
        : null;

    if ($sports_term_id) {

        // Find sports posts that have the same sport taxonomy term as the bulletin
        // Note: sport term is stored in an ACF in the sport post
        $sport_post_query_args = array(
            'post_type' => 'sport',
            'meta_query' => array(
                array(
                    'key' => 'related_sport_category', // name of custom field
                    'value' => $sports_term_id, // matches exactly "123", not just 123. This prevents a match for "1234"
                    'compare' => 'LIKE'
                )
            )
        );

        $sports_posts = get_posts($sport_post_query_args);

        if ($sports_posts) {
            $related_sport_icon_positive = get_field('sport_icon_positive', $sports_posts[0]->ID);
        }
    }

    return $related_sport_icon_positive;
}