July 2, 2005

URL Rewriting and mod_rewrite Not Working? Read On!

Okay, so I was trying to use mod_rewrite on Apache. That’s the program you use to take a URL like this: /photos/viewphoto?photoid=5 and turn it into something pretty like: /photos/viewphoto/5. It makes your URLs look better on the surface, but underneath the server still gets to play with all the messy query strings that keep your database-backed site humming.

So anyway, I was trying to do the example shown above, and every online tutorial showed me that I should put these lines in my .htaccess file:

RewriteEngine on
RewriteRule viewphoto/([0-9]+) viewphoto.html?id=$1 [NC]

But it was not working. Just was not. I would go to /photos/viewphoto/5, and get the viewphoto.html page with no query string attached to it. What could be wrong?

On a whim once, I changed the URL requested to /photos/viewPhoto/5. Notice the capital P? That made it work. But why? Why would it work with a capital letter, but not all in lower case?

After much walking around and banging my head, I finally figured out the reason. mod_rewrite only works if you’re getting a 404 error from your URL. When I requested /photos/viewphoto/5, the server could see that there was already a file named viewphoto.html. So it just served up that file, and didn’t get mod_rewrite involved at all. What I had to do was change the URL so that I’d get a 404 Page Not Found error if my rewrite rules weren’t there. So I did this:

RewriteEngine on
RewriteRule view/([0-9]+) viewphoto.html?id=$1 [NC]

And requested the page like so: /photos/view/5. Now, because there was no view.html, the server sent the request to mod_rewrite, and my rewrites happened like I wanted them to.

So be careful about this if you’re using mod_rewrite. Don’t give your “pretty” URLs a filename that actually exists on the system, or your rewrites will never work.

To see this at work, check out a sneak preview of my new Around Carson website. I’m using it in the photo section.

http://aroundcarson.com/photos/view/1
http://aroundcarson.com/photos/view/2

Filed under The Computer Vet Weblog

Comments (3)

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  1. pguoyizwqm says:

    Hello! Good Site! Thanks you! nycdtuvivvko

    Posted June 18, 2007 @ 8:40 am
  2. Binu.v.pillai says:

    Fine ,Verygood

    Actually i was looking a code like this.

    Posted February 2, 2008 @ 2:34 am
  3. Avebone says:

    Thank god for this post. Custom 404 directives are so common, that I would not have looked for this as a cause for my mod_rewrite not working. I also found that ‘AllowOverride All’ in the section of httpd.conf was needed in my case.

    Note: You can add ErrorDocument 404 to your .htaccess file(last command in the file) so that you can continue to have informative error pages for missing files.

    Thank Again.

    Posted January 15, 2009 @ 1:06 pm

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