Apache mod_rewrite/mod_redirect: convert URL with query parameters into an SEO-friendly URL. some query parameters are ignored

Question

As above.

might be best explained with an example:

• original URL (the order of the params is NOT consistent)

  • www.myhost.com/my-page?p1=v1&p2=v2&p3=v3
  • OR www.myhost.com/my-page?p2=v2&p1=v1&p3=v3
  • OR www.myhost.com/my-page?p3=v3&p1=v1&p2=v2

• If I visit any of the 3 sample URLs above, I want to get redirected to www.myhost.com/my-page/v1/v2

  • p3 was purposely ignored because it is not needed anymore.
  • in my real world URL, I have p4 to p6 parameters which are also ignored. I only wrote up to p3 for simplicity.

I've looked/searched the net but nothing comes close to what I'm trying to do. Thank you.

Answer 1

You can do it like the following using mod_rewrite:

RewriteEngine On

RewriteCond %{QUERY_STRING} (?:^|&)p1=([^&]+)
RewriteCond %1@%{QUERY_STRING} ^([^@]+)@(?:|.*&)p2=([^&]*)
RewriteRule ^/?(my-page)$ /$1/%1/%2 [QSD,R=302,L]

The first condition captures the value of p1 and passes this to the second condition that also captures the value of p2 . These are then used in the substitution string as %1 and %2 backreferences respectively.

The URL parameters can occur in any order.

@ (in the second condition) is just an arbitrary character that does not occur in v1 and so is used as a delimiter between v1 and the query string when searching for p2 .

All other URL parameters (ie. p3 .. pN ) are ignored (and discarded).

Parameter p1 must exist with a non-empty value (otherwise the resulting redirect will be ambiguous). p2 must also exist, but the value can be empty . eg. /my-page?p2=&p1=v1 would still be succesfully redirected to /my-page/v1/ .

The QSD flag discards the original query string from the request.

Depending on where these directives are being used (eg. directory or server context) and how the URL is ultimately being routed, you may need to add an initial condition to ensure that only direct requests (as opposed to rewritten requests) are processed.

For example, add the following as the first condition if required:

RewriteCond %{ENV:REDIRECT_STATUS} ^$
: