Apache mod rewrite

From ALSwiki

I had an older non-joomla which had built up many inbound links at other sites. Once converted to joomla, the page views dropped by about 80%. Watching the logs was painful as people came in on links that resulted in 404 errors. Here's what I did.

Enable Joomla's Search Engine Friendly URLs

From the admin interface:

 Site >> Global Configuration

Under SEO Settings, set "Search Engine Friendly URLs" to "yes". All URLs will now have a form something like:

 <your site name>/index.php/<section-name>/<category id>-<category-name>/<article id>-<article-name>

Special characters and spaces will be converted to legal characters. e.g. '"' becomes "q" and " " becomes "_". On my ourmexico.com site, the article "The Monarchs of Morelia" in the the "Travel" category of section "Stories" now has a url:

 http://www.ourmexico.com/index.php/stories/34-travel/44-the-monarchs-of-morelia

Add the redirection rules

These can go in an .htaccess file or in the Apache config file. There are many resources out there that provide instructions and examples.

• http://wiki.dreamhost.com/Mod_rewrite
• http://httpd.apache.org/docs/2.0/mod/mod_rewrite.html
• http://httpd.apache.org/docs/2.0/rewrite/rewrite_guide.html
• http://httpd.apache.org/docs/2.0/rewrite/rewrite_guide_advanced.html

Most of these assume you are trying to take an incoming "friendly URL" like /pies/apple/ and turn it into something like pies.php?type=apple. I had the opposite problem. My old site used "unfriendly urls" like "story.php?storyID=25". Apache stores the "story.php" as the request uri and the storyID=25 as the query string.

RewriteCond to the rescue!

RewriteCond allows you to set a series of conditions that must be true before the rewrite rule runs. I needed to test both the request uri and the query string. Here's a rule, that runs if the request uri is "story.php" and then checks to see if the query string contains the substring "20". In my case I didn't need a more complex regular expression, but could have easily applied one in the test. The R=301 sends a "Moved Permanently" code and the L says this is the last rule that should run if it matched.

 RewriteCond %{REQUEST_URI} ^.*story\.php$ 
 RewriteCond %{QUERY_STRING} 20
 RewriteRule ^.*$ /index.php/stories/34-travel/99-sierra-gorda-missions? [R=301,L]