Wordpress - Add class to Gutenberg Editor for Custom Post Types
This hook should add a single-[post_type] class to the body of the editor page.
add_filter('admin_body_class', function ($classes) {
//get current page
global $pagenow;
//check if the current page is post.php and if the post parameteris set
if ( $pagenow ==='post.php' && isset($_GET['post']) ) {
//get the post type via the post id from the URL
$postType = get_post_type( $_GET['post']);
//append the new class
$classes .= 'single-' . $postType;
}
//next check if this is a new post
elseif ( $pagenow ==='post-new.php' ) {
//check if the post_type parameter is set
if(isset($_GET['post_type'])) {
//in this case you can get the post_type directly from the URL
$classes .= 'single-' . urldecode($_GET['post_type']);
} else {
//if post_type is not set, a 'post' is being created
$classes .= 'single-post';
}
}
return $classes;
});