Sort PHP posts by PublishPress editorial metadata

sort-posts-by-meta.php

<?php
/**
 * @param WP_Query $query
 *
 * @return bool
 */
function pp_should_change_post_order($query)
{
    // Add a conditional here to filter when the queries should be filtered.
    return true;
}

add_filter('posts_fields', 'pp_order_posts_by_metadata_select', 10, 2);
function pp_order_posts_by_metadata_select($fields, $query)
{
    if (!pp_should_change_post_order($query)) {
        return $fields;
    }

    $fields .= ', IF(pm.meta_value > 0, pm.meta_value, 999999) AS cal_custom_position';

    return $fields;
}

add_filter('posts_join', 'pp_order_posts_by_metadata_join', 10, 2);
function pp_order_posts_by_metadata_join($join, $query)
{
    if (!pp_should_change_post_order($query)) {
        return $join;
    }

    global $wpdb;
    $join = "LEFT JOIN {$wpdb->postmeta} as pm ON (ID = pm.post_id AND pm.meta_key = '_pp_editorial_meta_number_position')";

    return $join;
}

add_filter('posts_orderby', 'pp_order_posts_by_metadata', 10, 2);
function pp_order_posts_by_metadata($orderby, $query)
{
    if (!pp_should_change_post_order($query)) {
        return $orderby;
    }

    $originalOrderby = $orderby;

    $orderby = 'cal_custom_position ASC';

    if (!empty($originalOrderby)) {
        $orderby .= ',' . $originalOrderby;
    }

    return $orderby;
}