据我所知，WordPress中的菜单处理程序使用菜单参数。你可以试着用这个。

使用参数过滤器，我们可以传递项的ID：

add_filter(
    \'nav_menu_item_args\',
    function( $args, $item, $depth ) {
        $args->item_id = $item->ID;

        return $args;
    },
    10,
    3
);

add_filter(
    \'walker_nav_menu_start_el\',
    function($item_output, $item) {
        if ( get_field( \'dropdown\', $item) == \'yes\' ) { 
            return \'<button aria-expanded="false" aria-controls="submenu-\'. $item->ID . \'" class="header__button">\' . $item->title . \'</button>\';
        }
        return $item_output;
    },
    10,
    2
);

class My_Nav_Menu_Walker extends Walker_Nav_Menu {
    /**
     * Starts the list before the elements are added.
     *
     * @see Walker::start_lvl()
     *
     * @param string   $output Used to append additional content (passed by reference).
     * @param int      $depth  Depth of menu item. Used for padding.
     * @param stdClass $args   An object of wp_nav_menu() arguments.
     */
    public function start_lvl( &$output, $depth = 0, $args = null ) {
        if ( isset( $args->item_spacing ) && \'discard\' === $args->item_spacing ) {
            $t = \'\';
            $n = \'\';
        } else {
            $t = "\\t";
            $n = "\\n";
        }
        $indent = str_repeat( $t, $depth );

        // Default class.
        $classes = array( \'sub-menu\' );

        // ! Get parent item ID:
        $id = isset( $args->item_id ) ? \' id="submenu-\' . absint( $args->item_id ) . \'"\' : \'\';

        /**
         * Filters the CSS class(es) applied to a menu list element.
         *
         * @since 4.8.0
         *
         * @param string[] $classes Array of the CSS classes that are applied to the menu `<ul>` element.
         * @param stdClass $args    An object of `wp_nav_menu()` arguments.
         * @param int      $depth   Depth of menu item. Used for padding.
         */
        $class_names = implode( \' \', apply_filters( \'nav_menu_submenu_css_class\', $classes, $args, $depth ) );
        $class_names = $class_names ? \' class="\' . esc_attr( $class_names ) . \'"\' : \'\';

        // ! Insert ID:
        $output .= "{$n}{$indent}<ul{$class_names}{$id}>{$n}";
    }
}

wp_nav_menu(
    array(
        \'container\' => false,
        \'theme_location\' => \'primary\',
        \'items_wrap\' => \'<ul class="header__nav-items header__nav-items--primary">%3$s</ul>\',
        \'walker\'  => new My_Nav_Menu_Walker()
    )
);