How to set the currently active page in the menu including parents

Question

I have the following problem:

There is a custom post type. There are several pages each listing some of the posts based on some post criteria (custom WP_Query).

When I click on a link to open the full version of the post, the parent page of the post is . But for the sake of user experience it should be the parent page the user came from and that should be highlighted in the menu.

I partly solved this problem by adding "?parent=" to the links and parsing that in a filter:

// Fix menu parents
add_filter('nav_menu_css_class', function($classes, $item, $args) {
    if (!isset($_GET['parent']) || empty($_GET['parent'])) return $classes;
    if ($item->object_id == $_GET['parent']) {
        $classes[] = "current_page_item";
        $classes[] = "current-menu-item";
    }
    return $classes;
}, 10, 3);

Now here comes the case, where this doesn't work: When the parent is inside a sub menu then the parent of that sub menu does not get marked as active and the sub menu remains closed. So I need to add current-page-ancestor current-menu-ancestor current-menu-parent current_page_parent current_page_ancestor to the parent menu item inside that filter function.

So what I thought is, I need a $item->has_child($_GET['parent']) which does not exist obviously.

Do you guys have any ideas about this?

Edit: I added a dirty client side JavaScript fix to solve this. But I would still prefer a server side fix.

jQuery(function() {
    jQuery(".current-menu-item").parents("li").addClass("current-page-ancestor current-menu-ancestor current-menu-parent current_page_parent current_page_ancestor");
});

Answer 1

It sounds like you may be over-complicating this. If your goal is to highlight a post's top parent while the post is listed in a sub-menu of said parent, then this is a CSS problem, not a wordpress one. The following should work:

.current-menu-parent a, .current-menu-ancestor a {
 color: #7dca8d;
}