Sanitize query using preg_replace but allow some special characters

I am sanitizing a query using the following regex. However, I need some special characters to be allowed in the query.

In particular I need to allo开发者_运维技巧w: Ä, ä, Ö, ö, Ü, ü, ß

What do I need to change to achieve this?

$query = preg_replace('/[^-a-zA-Z0-9_\/]/', '', $_GET['destination']);

/[^\w-\p{L}\p{N}\p{Pd}]/

This will match anything that's NOT an alphanumeric character (including UTF-8 letters) as well as the dash (-).

Your question is really about how to support multibyte characters in preg expressions, see:

• Are the PHP preg_functions multibyte safe?
• preg_match and UTF-8 in PHP