.htaccess - dependancy in rewrite rules

Question

I have the following rewritiing rule for every image URL given within the HTML code

RewriteRule ^([^tn].*\.(gif|jpg|png))$ /media/k2/watermark.php?image=$1&watermark=watermark.png [NC]

I want to add some optional parameter 'partner' that will be injected as a GET parameter to the watermark.php script. But the problem is it won't be added to any of the image URL (cause I don't want to modify every code line that displays an image) but to the website URL. Is it possible to make a dependancy in .htaccess that will work like this:

'If the browser URL has the "partner" parameter inject in into every image URL as well'

Is is possible at all?

Answer 1

Yes it is possible just add QSA (Query String Append) flag to your rule:

RewriteRule ^([^tn].*\.(gif|jpg|png))$ /media/k2/watermark.php?image=$1&watermark=watermark.png [NC,L,QSA]

QSA flag will make sure to keep any browser supplied query parameters while adding new ones from your rewrite rules.