How do I preserve the existing query string in a mod_rewrite rule

Question

I'm trying to rewrite an url from:

http://domain.com/aa/whatever/whatever.php
to
http://domain.com/whatever/whatever.php?language=aa

However, depending on existing $_GET variables, it either has to be ?language or &language.

To do this, I use 2 regexes with the [L] flag:

RewriteRule ^([a-z]{2})/(.*\.php\?.*) /$2&language=$1 [L]
RewriteRule ^([a-z]{2})/(.*) /$2?language=$1 [L]

The second one works as expected... The first one however is never hit (it falls through to the second regex, which does hit), even though Regex Coach does show me that it should.

edit:

If just read that I need to use two backslashes to escape the question mark. If I do this, it does hit on the first regex but never find the other GET variables.

Answer 1

From the documentation for mod_rewrite the pattern in RewriteRule matches against the part of the URL after the hostname and port, and before the query string so the query string is not included. That is why you don't get the other variables.

To add a new query string parameter language=xx whilst preserving any existing query string you need to use the QSA flag (query string append). With this flag, just one rule based on your second case should be sufficient:

RewriteRule ^([a-z]{2})/(.*) /$2?language=$1 [QSA]