Shortcode to display all child pages of a given Wordpress directory

list-wp-child-pages.php

// Shortcode to display child pages (add this to functions.php)
function list_child_pages($atts) {
    $atts = shortcode_atts(array(
        'parent_id' => 0,
    ), $atts, 'child-pages');

    $args = array(
        'post_type' => 'page',
        'post_parent' => $atts['parent_id'],
        'orderby' => 'menu_order',
        'order' => 'ASC',
    );

    $child_pages = new WP_Query($args);
    
    if ($child_pages->have_posts()) {
        $output = '<ul>';
        while ($child_pages->have_posts()) {
            $child_pages->the_post();
            $output .= '<li><a href="' . get_permalink() . '">' . get_the_title() . '</a></li>';
        }
        $output .= '</ul>';
    } else {
        $output = 'No child pages found.';
    }

    wp_reset_postdata();

    return $output;
}
add_shortcode('child-pages', 'list_child_pages');