Wordpress Search Filter Only for Page with Child of Child of Child of Child of Child

Question

after browsing question from this site I found the workaround for this:

function SearchFilter($query) {
    if ($query->is_search) {
        global $post;
        $query->set( 'post_parent', 21 );
    }
    return $query;
}
add_filter('pre_get_posts','SearchFilter');

When I do this, its only search child of parent 21 not child of child of parent 21.

Also, query_vars only accept single value for post_parent.

any solution for this is highly appreciated.

thanks

Answer 1

You can probably do something like this. It's probably less efficient, but should find all descendants of a given page rather than just direct children.

function find_descendants($post_id) {
    $descendant_ids = array();
    $pages = get_pages("child_of=$post_id");
    foreach ($pages as $page) { array_push($descendant_ids, $page->ID); }
    return $descendant_ids;
}

function SearchFilter($query) {

    if ($query->is_search) {
        $query->set ( 'post__in', find_descendants(21) );
    }
    return $query;
}
add_filter('pre_get_posts','SearchFilter');