Get Primary Taxonomy Term set by Yoast SEO

README.md

This have been modified to gracefully fail when used on Post types that do not support the described taxonomy.

yoast-primary-term.php

/**
 * Returns the primary term for the chosen taxonomy set by Yoast SEO
 * or the first term selected.
 *
 * @link https://www.tannerrecord.com/how-to-get-yoasts-primary-category/
 * @param integer $post The post id.
 * @param string  $taxonomy The taxonomy to query. Defaults to category.
 * @return array The term with keys of 'title', 'slug', and 'url'.
 */
function get_primary_taxonomy_term($post = 0, $taxonomy = 'category')
{
    if (!$post) {
        $post = get_the_ID();
    }

    $post_type = get_post_type($post);
    $taxonomies = get_object_taxonomies($post_type);

    // FAIL if the post does not support the taxonomy
    if (!in_array($taxonomy, $taxonomies)) {
        return false;
    }

    $terms = get_the_terms($post, $taxonomy);
    $primary_term = array();

    if ($terms) {
        $term_display = '';
        $term_slug = '';
        $term_link = '';
        if (class_exists('\WPSEO_Primary_Term')) {
            $wpseo_primary_term = new \WPSEO_Primary_Term($taxonomy, $post);
            $wpseo_primary_term = $wpseo_primary_term->get_primary_term();
            $term = get_term($wpseo_primary_term);
            if (is_wp_error($term)) {
                $term_display = $terms[0]->name;
                $term_slug = $terms[0]->slug;
                $term_link = get_term_link($terms[0]->term_id);
            } else {
                $term_display = $term->name;
                $term_slug = $term->slug;
                $term_link = get_term_link($term->term_id);
            }
        } else {
            $term_display = $terms[0]->name;
            $term_slug = $terms[0]->slug;
            $term_link = get_term_link($terms[0]->term_id);
        }
        $primary_term['url'] = $term_link;
        $primary_term['slug'] = $term_slug;
        $primary_term['title'] = $term_display;
    }
    return $primary_term;
}