Body class on page and descendants

body_class_descendants.php

// Add class of "hub-$template_colour" to a page and its descendants
// Adapted from http://techtabby.com/how-to-add-body-class-to-page-and-descendants-wordpress/
function tend_parent_body_class( $classes ) {
    	if( is_page() ) { 
        	$parents = get_post_ancestors( get_the_ID() );
			    $id = ($parents) ? $parents[count($parents)-1]: get_the_ID();
		      if ($id) {
            if(get_field('colour_picker', $id )) {
                $template_colour = get_field('colour_picker', $id);
                $classes[] = 'hub-' . $template_colour;
            }
		      } else {
            $ancestor_id = get_the_ID();
            if(get_field('colour_picker', $ancestor_id )) {
                $template_colour = get_field('colour_picker', $ancestor_id);
                $classes[] = 'hub-' . $template_colour;
            }
		      }
	}
 
	return $classes;
}

add_filter( 'body_class', 'tend_parent_body_class' );