Apache Cookbook, 2nd Edition

5.20. Rewriting Elements between Path and Query String

Problem

You want to turn portions of a URL into query-string parameters, or vice versa.

Solution

To rewrite http://example.com/path/to/5 to http://example.com/path/to?id=5:

RewriteRule "^(/path/to)/(\d+)" "$1?id=$2" [PT]

To go the other way:

RewriteCond "%{QUERY_STRING}" "\bid=(\d+)\b"
RewriteRule "(/path/to)" "$1/%2" [PT,QSA]

Tip

Note that the arguments to the RewriteRule directives need to be structured differently if they occur in a .htaccess file. The above solution illustrates the syntax if they’re put into the server-wide configuration files.

Discussion

It is quite common for sites to have to change the way URLs are structured, either moving portions into or out of the query-string portion. This often becomed necessary when the underlying software is changed—say, from one blogging package to another. The new software requires URLs to be in a different format, but you don’t want to invalidate all the old-style URLs that might be bookmarked or otherwise spread around the Web.

This is a perfect application for mod_rewrite, and quite simple to accomplish as well, as demonstrated in the solution.

See Also

• http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html