给你。将此添加到函数。php并从任何您想要的地方调用它。

function get_post_primary_category($post_id, $term=\'category\', $return_all_categories=false){
        $return = array();

        if (class_exists(\'WPSEO_Primary_Term\')){
            // Show Primary category by Yoast if it is enabled & set
            $wpseo_primary_term = new WPSEO_Primary_Term( $term, $post_id );
            $primary_term = get_term($wpseo_primary_term->get_primary_term());

            if (!is_wp_error($primary_term)){
                $return[\'primary_category\'] = $primary_term;
            }
        }

        if (empty($return[\'primary_category\']) || $return_all_categories){
            $categories_list = get_the_terms($post_id, $term);

            if (empty($return[\'primary_category\']) && !empty($categories_list)){
                $return[\'primary_category\'] = $categories_list[0];  //get the first category
            }
            if ($return_all_categories){
                $return[\'all_categories\'] = array();

                if (!empty($categories_list)){
                    foreach($categories_list as &$category){
                        $return[\'all_categories\'][] = $category->term_id;
                    }
                }
            }
        }

        return $return;
    }