Order a query by post type

// Order a query by an post type
// You can just use the 'orderby' query argument to order by 'type' (= post type) to order a query by post type, 
// but only alphabetically, with the order set to ASC or DESC. 
// If you need an arbitrary order, you can use the following:

function order_search_by_posttype( $orderby, $wp_query ) {

  global $wpdb;

  // filter the correct query by using the original post_type argument as check
  if ( $wp_query->query_vars['post_type'] == [
    ] ) {
    // set the new order of the post types
    $orderby =
            CASE WHEN {$wpdb->prefix}posts.post_type = 'job_listing' THEN '1'
                 WHEN {$wpdb->prefix}posts.post_type = 'product' THEN '2' 
                 WHEN {$wpdb->prefix}posts.post_type = 'portfolio' THEN '3' 
            ELSE {$wpdb->prefix}posts.post_type END ASC, 
            {$wpdb->prefix}posts.post_title ASC";

  return $orderby;

add_filter( 'posts_orderby', 'order_search_by_posttype', 10, 2 );