Get page IDs from nav items

I am trying to get all the IDs in my navigation and convert it to a string so that I can use it with wp_query to get the pages that are only listed in the nav. The code to get the IDs:

$menu_name = 'primary';

if ( ( $locations = get_nav_menu_locations() ) && isset( $locations[ $menu_name ] )) {
    $menu = wp_get_nav_menu_object( $locations[ $menu_name ] );
    $menu_items = wp_get_nav_menu_items($menu->term_id);
}

foreach ( $menu_items as $menu_item ) {
    $numbers[] = $menu_item->ID;
}

$number = implode(',',$numbers);

But it is returning the wrong numbers. When I go to the admin area and hover my mouse over the pages, the number that shows up in the address bar on the bottom of the screen doesn’t match. What am I doing wrong?

Solutions Collecting From Web of "Get page IDs from nav items"

Menu items are stored in the posts table with a post_type of nav_menu_item. So, what you are returning is the ID of the menu item itself, not what it points to.

The page/post ID that the menu item refers to is stored in the postmeta table, with a post_id that matches the menu item ID and meta_key = _menu_item_object_id. The easiest way to get the meta_value (ie the page being pointed to by the menu item) is to use something like this:

$numbers[] = get_post_meta( $menu_item->ID, '_menu_item_object_id', true );