Rewrite Urls with question mark and ampersand - .htaccess

Question

On my website I have categories with urls like so
www.example.com/?foo and www.example.com/?bar
In these categories I have articles with urls like this:
www.example.com/?foo&nr=12
and groups with urls like this:
www.example.com/?foo&group=somegroup
I am trying to rewrite
/foo to /?foo, /bar to ?bar etc.; /bar/12 to /?bar&nr=12 etc. and /foo/somegroup to /foo&group=somegroup
It should work both with and without final slash.
The (admittedly clueless) things I tried either did nothing or resulted in a server error. At some points I also tried just getting the &nr=xx bit or simply the categories. Some of them are:
RewriteCond %{QUERY_STRING} (?:^|&)([^&]+) RewriteRule /?(.*) %1/$1
[QSA]
RewriteRule ^/([^/]+)/([^/]+)$ /?$1&nr=$2
RewriteRule ^/([^/]+) ?nr=$1 [L]

Answer 1

Ok, assuming the file handling the queries is index.php and foo and bar don't change to something else, you could start like this:
RewriteEngine On
RewriteBase /
RewriteRule ^foo$ foo/ [NC,R]
RewriteRule ^foo/$ index.php?foo [NC,L]
RewriteRule ^foo/([A-Za-z0-9_-]+)$ foo/$1/ [NC,R]
RewriteRule ^foo/([A-Za-z0-9_-]+)/$ index.php?foo&group=$1 [NC,L]
Now you should be able to do the bar part on your own!
Btw. if you really want your query string to only be ?foo (without a value, like so: ?foo=somevalue) you'll have to check for foo's existence differently than you would for e.g. the somegroup part.