Unique native function to get the sub menu part in wp_nav_menu

We were working on our WordPress project and we had found a problem that when using wp_nav_menu(), there is no native function to get submenu part in another element. eg: sidebar. We found a solution which can be used to avoid this problem. Please find below code.

Just add the ‘submenu’ in the arguments for the wp_nav_menu(). Then the label name of the top-level menu that has the submenu that you want to list.

// Usage:
$args = array(
    'menu'    => 'Menu Name',
    'submenu' => 'About Us',
);

wp_nav_menu( $args );

Paste this in function.php

add_filter( 'wp_nav_menu_objects', 'submenu_limit', 10, 2 );

function submenu_limit( $items, $args ) {

    if ( empty($args->submenu) )
        return $items;

    $parent_id = array_pop( wp_filter_object_list( $items, array( 'title' => $args->submenu ), 'and', 'ID' ) );
    $children  = submenu_get_children_ids( $parent_id, $items );

    foreach ( $items as $key => $item ) {

        if ( ! in_array( $item->ID, $children ) )
            unset($items[$key]);
    }

    return $items;
}