Replace Content of Sidebar on Custom Post Type

Question

sorry, if this is a stupid question, but I am relatively new to php and wordpress development.

I am writing a plugin with a custom post type (course) where a parent page is the course overview and the child pages are the lessons.

Now my aim is to replace the content of the sidebar. If the page is a parent cpt then content of sidebar A should be displayed. If the page is a child cpt then the content of sidebar B should be displayed.

So what I am trying to do is to stop loading the widgets of the normal theme sidebar and replace them with the widgets from sidebar a or b.

I was able to:

• create a dropdown in the backend, where the sidebar which should be replaced can be selected.
• register two new sidebars (in design > widgets) (with register_sidebar).
• check if the page is a parent cpt or a child ctp
  if ( is_singular('courses') && $post->post_parent && is_active_sidebar( 'courses-lessons-sidebar' ) ) or
  if ( is_singular('courses') && ! $post->post_parent && is_active_sidebar( 'courses-overview-sidebar' ) )

But what I do not understand is, how to tell WordPress to stop loading the widgets from the normal sidebar, but from one of the new sidebars!?

I tried a lot of things and thought I found a solution with injecting the widgets with dynamic_sidebar_before and then stop rendering the normal sidebar with "exit", but this leads to unwanted problems (e.g. mobile menu is no longer visible, etc.)

And by the way: I would need the solution to be theme independent :)

I really hope that there is someone out there who can help me! Thank you very much in advance! Best regards! Tioata

Answer 1

After a lot of trying and testing, I think I've found a solution:

add_filter( 'sidebars_widgets', 'exchange_sidebars', 10);

function exchange_sidebars( $sidebars_widgets ){
    global $post;
    // Define the sidebar which should be exchanged
    $selected_sidebar = 'sidebar-1'

    // IF we are on a custom post type
    // AND it is a Child Page (= page has post_parent)
    // THEN change selected sidebare with courses-lessons sidebar
    if ( is_singular('courses') && $post->post_parent && $sidebars_widgets['courses-lessons-sidebar'] ) {
        $sidebars_widgets[$selected_sidebar] = $sidebars_widgets['courses-lessons-sidebar'];

    // IF we are on a custom post type
    // AND it is a Parent Page (= page has no post_parent)
    // THEN change selected sidebare with courses-overview sidebar
    }elseif( is_singular('courses') && !$post->post_parent && $sidebars_widgets['courses-overview-sidebar'] ) {
        $sidebars_widgets[$selected_sidebar] = $sidebars_widgets['courses-overview-sidebar'];
    }
    return $sidebars_widgets;
}

Just in case someone else is interested in the solution ;)