List All Custom Post Types Posts in Nav Menu Dynamically

Question

Ive successfully added all posts (of a custom post type) to my wordpress menu using this method: https://codeseekah.com/2012/03/05/list-all-posts-in-wordpress-navigation-menu/

Everything is working great. Unfortunately I get this error when saving the menu in wp admin: "The given object ID is not that of a menu item." I get a long list of like 20 of them (one error for each menu item).

This is what I have in my functions file:

/**
 * List all posts in wp nav menu
 * @link https://codeseekah.com/2012/03/05/list-all-posts-in-wordpress-navigation-menu/
 * @param  [type] $items [description]
 * @param  [type] $menu  [description]
 * @param  [type] $args  [description]
 * @return [type]        [description]
 */
/* take care of the urls */
add_filter( 'wp_get_nav_menu_items', 'services_menu_filter', 12, 3 );
function services_menu_filter( $items, $menu, $args ) {
    /* alter the URL for cpt-archive objects */

    $menu_order = count($items); /* Offset menu order */
    $child_items = array();

    foreach ( $items as &$item ) {
        if ( $item->title != '##services##' ) continue;
        $item->url = '/services/';
        $item->title = 'Services';

        foreach ( get_posts( 'post_type=services&numberposts=-1' ) as $post ) {
            $post->menu_item_parent = $item->ID;
            $post->post_type = 'nav_menu_item';
            $post->object = 'custom';
            $post->type = 'custom';
            $post->menu_order = ++$menu_order;
            $post->title = $post->post_title;
            $post->url = get_permalink( $post->ID );
            /* add children */
            $child_items []= $post;
        }
    } 
    return array_merge( $items, $child_items );
}

Any ideas to get rid of the wordpress menu error notifications? Everything works fine and I could live with it, but i dont want to throw off the client if/and when they see all the errors. Yes, I thought about hiding the errors with CSS, but thats just not good enough.

The web host is Kinsta. I've tried adding the following to wp-config.php:

/** Memory Limit */
define('WP_MEMORY_LIMIT', '128M');

Thanks!

Answer 1

I think you're only adding the custom posts to the nav menu on the front-end and not on the back-end/wp-admin.

Therefore, you can use is_admin() to see if the hook wp_get_nav_menu_items is being called on the front-end or from an "admin" page such as the Appearance → Menus page.

So, replace this:

function services_menu_filter( $items, $menu, $args ) {
    /* alter the URL for cpt-archive objects */

..with this one:

function services_menu_filter( $items, $menu, $args ) {
    if ( is_admin() ) {
        return $items;
    }

    /* alter the URL for cpt-archive objects */

Alternatively, replace this:

add_filter( 'wp_get_nav_menu_items', 'services_menu_filter', 12, 3 );

..with this one:

if ( ! is_admin() ) {
    add_filter( 'wp_get_nav_menu_items', 'services_menu_filter', 12, 3 );
}