Yoast Primary and Secondary Terms

yoast-primary-and-secondary.php

<?php

/**
 * Post Categories
 *
 * Get Primary term, if set, and other terms for a post (with Primary Term excluded)
 *
 * @category Theme
 * @package  MattRadford/mattradford
 * @author   Matt Radford <matt@mattrad.uk>
 * @license  https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GPL-2.0+
 * @link     https://github.com/10degrees/10degrees-base
 * @since    2.0.0
 */
class PostCategories
{
    /**
     * Post ID
     */
    public int $postID;

    /**
     * Primary Term
     */
    public object $primaryTerm;

    /**
     * Secondary Terms
     */
    public array $secondaryTerms;

    /**
     * Constructor
     */
    public function __construct($postID)
    {
        $this->postID = $postID;
        $this->getYoastPrimaryTerm();
        $this->getAllSecondaryTerms();
    }

    /**
     * Get Yoast Primary Category
     *
     * @return object $primaryTerm
     */
    public function getYoastPrimaryTerm()
    {
        if (class_exists('WPSEO_Primary_Term')) {
            $wpseoPrimaryTerm = new \WPSEO_Primary_Term('category', $this->postID);
            $wpseoPrimaryTerm = $wpseoPrimaryTerm->get_primary_term();
            $term = get_term($wpseoPrimaryTerm);
            if (!is_wp_error($term)) {
                $this->primaryTerm = $term;
            }
        }
    }

    /**
     * Get assigned Categories, exclude Primary if set
     *
     * @return object $primaryTerm
     */
    public function getAllSecondaryTerms()
    {
        $this->secondaryTerms = get_the_terms($this->postID, 'category');
        if (!class_exists('WPSEO_Primary_Term')) {
            return;
        } else {
            if ($this->primaryTerm !== null) {
                $allTerms = $this->secondaryTerms;
                $primaryTermId = $this->primaryTerm->term_id;
                $allTermIds = array_column($allTerms, 'term_id');
                if (\in_array($primaryTermId, $allTermIds)) {
                    if (($key = array_search($primaryTermId, array_column($allTerms, 'term_id'))) !== false) {
                        unset($allTerms[$key]);
                        $this->secondaryTerms = $allTerms;
                    }
                }
            }
        }
    }
}