Modern database driven web sites implement SEO-friendly URLs emulating static directories and files. Switching to such “clean” URLs enables good indexing by search engines, makes URLs more user-friendly and hides the server-side language. For example, this clean URL may refer to the page in some product directory:
http://somesite.com/products/network/router.html
In fact, there is no /products/network folder on the server and no router.html file at all. The page is generated by server script using database query for “network” product category and “router” product. But who calls the script and where it gets the query parameter values?
This technique is usually referred as “URL rewriting”. It allows web server to recognize what information was requested by parsing the URL string. Apache and PHP allow multiple options to implement URL rewriting. So which one is the best?
Configuring mod_rewrite via .htaccess file
This is perhaps the most used way to implement rewriting especially to upgrade legacy web sites.
Consider we already have products.php script that can take category and product parameters from $_GET array. We just need to convert the request URI invisibly to the user:
/products/network/router.html => /products.php?category=network&product=router
Apache already has built-in URL rewriting engine: mod_rewrite. It allows specifying rules based on regular expressions for URL parsing, transformation and even redirect. You just need to create or modify .htaccess file to use mod_rewrite:
RewriteEngine On RewriteRule ^products/(\w+)/(\w+)\.html products.php?category=$1&product=$2 [L]
Well, now the script can continue using $_GET array to get category and product name as if it was called with a dynamic URL and no modification is required to the script code.
Oops! What happened with my CSSs, JSs, images and relative links??! Don’t worry, I explained the problem and solutions in my post SEO-Friendly URLs and Relative Links.
While usage of mod_rewrite is very easy solution, it may introduce some problems with growing complexity of rewrite rules:
- It’s very hard to debug .htaccess code.
- Extended regular expression syntax may be incompatible with old Apache versions. I noticed some problems with GoDaddy shared hosting, which actually uses Apache v1.3.
- You may also want to automatically correct user typos in URLs against database contents that is almost impossible with mod_rewrite only. (But you can still try mod_spelling.)
All those problems could be resolved by moving URI parsing logic to PHP code allowing implementation of more complex rewrite rules and debugging with native PHP tools.
Parsing REQUEST_URI by PHP code
Apache web server also allows you to use URLs like this one:
http://somesite.com/products.php/network/router.html
Apache will call products.php script and ignore the reminder path. The script can get it by parsing $_SERVER[‘REQUEST_URI’]:
//Remove request parameters:
list($path) = explode('?', $_SERVER['REQUEST_URI']);
//Remove script path:
$path = substr($path, strlen($_SERVER['SCRIPT_NAME'])+1);
//Explode path to directories and remove empty items:
$pathInfo = array();
foreach (explode('/', $path) as $dir) {
if (!empty($dir)) {
$pathInfo[] = urldecode($dir);
}
}
if (count($pathInfo) > 0) {
//Remove file extension from the last element:
$last = $pathInfo[count($pathInfo)-1];
list($last) = explode('.', $last);
$pathInfo[count($pathInfo)-1] = $last;
}
Now $pathInfo variable contains elements of the reminder path. You can use it to specify database query parameters.
But what if they are invalid? This way you need to raise “file not found” error from PHP script. For example:
if (count($pathInfo[0] < 2) {
header('HTTP/1.0 404 not found');
exit;
}
Alternatively, you can fire a redirect to some error page.
I also recommend to use structural error handling to catch “path not found” exceptions that could be raised deep in your code.
Notice that PHP allows read/write access to $_GET array and you can use this ability to make legacy without a change:
$_GET['category'] = $pathInfo[0]; $_GET['product'] = $pathInfo[1];
But how to get rid of that “.php” in the URL? You can do this by renaming “products.php” file to “products” (w/o an extension) and modifying .htaccess file to tell Apache that “products” is actually a PHP script:
<FilesMatch "^products$">
ForceType application/x-httpd-php
</FilesMatch>
Hmm.. don’t like the solution but this way URLs like http://somesite.com/products/network/router.html will work OK.
At some moment you may want to get rid of that “products” directory to make URLs shorter like http://somesite.com/network/router.html. You may also want have other directories like news, blog, etc on the same site.
Can we parse all virtual URLs in the same PHP script? Sure, we can do that!
Combining powers of mod_rewrite and PHP
The best way to implement SEO-friendly URLs is to combine powers of mod_rewrite and PHP. This way you gain full control over URL rewriting with full power of PHP language.
You just need to have very simple code in .htaccess file:
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . index.php [L,QSA]
The code is proven compatible with older Apache versions like that on GoDaddy shared hosting.
Now you will process any request for virtual URI in index.php file. You can get the URI requested from $_SERVER[‘REQUEST_URI’] and parse it with the code almost the same as above:
//Remove request parameters:
list($path) = explode('?', $_SERVER['REQUEST_URI']);
//Remove script path:
$path = substr($path, strlen(dirname($_SERVER['SCRIPT_NAME']))+1);
//Explode path to directories and remove empty items:
$pathInfo = array();
foreach (explode('/', $path) as $dir) {
if (!empty($dir)) {
$pathInfo[] = urldecode($dir);
}
}
if (count($pathInfo) > 0) {
//Remove file extension from the last element:
$last = $pathInfo[count($pathInfo)-1];
list($last) = explode('.', $last);
$pathInfo[count($pathInfo)-1] = $last;
}
This way you can implement very intellectual logic to provide most smart, short and flexible document naming schemes on your web site. For example, you can make all these (and many similar) URLs referring (or better redirecting) to the same page:
- http://somesite.com/products/network/router.html
- http://somesite.com/products-network/router/
- http://somesite.com/networks/router/
- http://somesite.com/router
At the same time, the code can recognize that http://somesite.com/20091010/router/ refers to a news article just because there is a corresponding record in the news table.
You can also combine URL parsing logic with content negotiation logic recognizing client’s user-agent.
As far as you do all virtual URL parsing with PHP, you can use native PHP debuggers and logging for it. You don’t need to care about physical files like images, CSSs or static pages as the .htaccess code above leaves them alone. But you still need to care about file not found errors as explained in the previous section.
Conclusion
There are multiple ways to implement URL rewriting with Apache and PHP and you need to make a choice depending on your project requirements. Having all URL parsing in the same PHP script is the most recommended solution as it allows to implement the most complex, expendable and easy-to-debug URL rewriting logic.
We use .htaccss for all our friendly URL needs. Good post.
Hmm this is an interesting way of doing it. I normally use htacess (a bit differently than how you showed above) and I notice if you have two urls with similar keywords, it gets confused and takes you to one page instead of to. For example:
http://www.site.com/amber-is-cool
and
http://www.site.com/amber-is-mean
would take you to the same page. This can normally be changed, unless a client specifically wants a page to be the similar name.
Amber, can you describe the way you use htaccess? I’m still researching this subject.
I think there is nothing bad in having multiple URL aliases for the same page. But it’s better to make them redirecting to original URL to do not confuse the user as well as search engines.
I’m going to write another post on how such a redirect could be implemented with PHP.
Great article! This can certainly be helpful for users wanting search engine friendly URL’s on Linux or Unix hosting!
Update: I updated URI parsing code as there were some minor problems with it and added PHP example for the last method.
here is a similar method for using php to do most of the work:
http://forum.modrewrite.com/viewtopic.php?t=2521
Great article, thanks !
Zend Framework follow this mod_rewrite trick.
@Anton Oliinyk ,http://net.tutsplus.com/tutorials/other/a-deeper-look-at-mod_rewrite-for-apache/ got deep inside it.And every example is very useful.
(I hate china GFW ,@_@!)
It’s quite interesting article. I’m just curious how long are in interested in this subject ? I saw many blogs but Your’s it’s really informative.
Not so much time, actually. I searched the web for some comprehensive guide but found only partial explanations. So, I decided to write some note about that.
BTW, modern CMS’es and frameworks like WordPress or Zend Framework use similar mod_rewrite+PHP solutions but nobody wrote about that.
Do you know of anyway with htaccess to disable someone from using your domain to point to their own website on the same server? Ex: they use YOURDOMAIN.com to promote their PHISHING WEBSITE.COM by using this simple URL to send users : YOURDOMAIN.COM/~phishing/file.html
Any help would be greatly appreciated. Thanks
Looks like a side-effect of mod_userdir Apache module.
I think it’s no possible to stop with rewriting as the request never actually comes to your virtual host.
I suggest to ask your hosting provider to disable mod_userdir at least for your virtual host or to move to another hosting with mod_userdir disabled.
When i do this my site page goes into infinite loop looking for sub-directories and never opens the page. What’s wrong?
Katie, what exactly do you do?
You can email me sample code and I’ll take a look.
Hi,
Thanks for sharing this.
I have some questions I hope you can clarify.
I normally user rewrite mod with the unique numeric ID of the information I need, in order to query the mysql database.
With your example there is no numeric ID.
Now I’m confused 🙂
There is where my questions start.
Imagine I have a product
products.php?category=network&product=1
products.php?category=network&product=2
How can I make
/products/network/router.html open products.php?category=network&product=1
and
/products/network/cable.html open products.php?category=network&product=2
Thanks in advance
Hi!
You’ll have to query database using string IDs you use in URLs. Say, you can add a field ‘slug’ to category and product tables and look up records by that field.
Hi,
Thanks for the reply.
Could you kindly provide an example please?
I would like to keep the “fake URL” with out any numeric values.
Say, category table is:
id, slug, label
1, appliances, Appliances
2, network, Network
3, video, Video
…
And product table is:
id, category_id, slug, label, description
1, 1, blender, Blender, This is cool blender
2, 1, water-filter, Water Filter, This is cool water filter
3, 2, router, D-Link DIR-300, This is not so cool network router
…
Now you get request for /products/network/router.html
which is rewritten to products.php?category=network&product=router
Now let’s query product data:
$rs = $db->query("
SELECT `product`.* FROM `product`
JOIN `category` ON `product`.`category_id` = `category`.`id`
WHERE `product`.`slug` = '{$db->real_escape_string($_GET['product'])}' AND `category->slug` = '{$db->real_escape_string($_GET['category'])}'");
The result set will contain single record for the product with ID 3.
Hope that helps.
Hi.
So I figure the slug field would be the same thing has the numeric ID field, only that contains words.
Making sure there are no duplicate slag names also.
Ill give it a try.
Thanks for the example.
Yes, you’re right. Definitely some way is needed to establish a match between human-friendly URL directory names and database records. So “slug” fields do.
The only little difference in this particular sample case is that product slug have to be unique within category only as we use both category and product slugs to find a product. So there could be products with the same slug in other categories.
am i missing something here, because im having better luck with this
if(!empty($_SERVER[‘QUERY_STRING’])){
list($root,$path) = explode(‘?’, $_SERVER[‘REQUEST_URI’]);
//rest of code here
have they changed the functionality of list()? because when i run it as suggested the script path is already stripped, and when the substr strips it even further, i end up with “ndex.php”
see var dumps for $path and $pathInfo below
string(10) “/index.php”
array(1) { [0]=> string(8) “ndex.php” }
Definitely, nothing changed with list().
I believe, you have to go back to my original code as it is:
list($path) = explode(‘?’, $_SERVER[‘REQUEST_URI’]);
As you changed it the path now actually goes to your $root variable.
i think the reason i was having hard time was because were talking about 2 different types of url querys,
i need a solution for this type of url
wolfdogg.org/?section=iditarod&subject=idit_weather
i dont use the work index.php, but i want the code to be cross compatible for both /? and /index.php?
and i need to figure out a system whats the best way to utilize those vars. currently, ‘section’ is the first subdirectory and ‘subject’ is the page , in this case, wolfdogg.org/iditarod/idit_weather.php
any suggestions on how to modify the code to adapt?
curently using
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . index.php [L,QSA]
list($root,$path) = explode(‘?’, $_SERVER[‘REQUEST_URI’]);
//Explode path to directories and remove empty items:
$pathInfo = array();
foreach (explode(‘&’, $path) as $dir) {
if (!empty($dir)) {
$pathInfo[] = urldecode($dir);
}
}
looks like a good start
var dump looks like this
array(2) { [0]=> string(16) “section=iditarod” [1]=> string(20) “subject=idit_weather” }
what im hoping to have is the url rewritten to this automatically
wolfdogg.org/iditarod/idit_weather
without changing all my links in the source code
Rewriting incoming request URL and generating link URLs for rendering on web pages are two different things (yet related of course).
I believe, you have no automatic way if you have URLs hardcoded. You might filter HTML output to replace URLs on-fly but it’s too tricky and will drain system resources.
I suggest encapsulating URL generation into a function or better a class so that you can edit it from single place in future.
Learning MVC best practices also might help. I especially like how Zend Framework handles it as it uses the same class set for parsing incoming request URL as well as for generating URLs of links on pages.
Hello my good friends !
I used these codes in file .htaccess
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . index.php [L,QSA]
but this error appeared (500 internal server error)
” Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster@gmail.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Apache/2.2.4 (Win32) PHP/5.2.1 Server at localhost Port 80 ”
explain me why
would you may send me full code with out errors?
thanks a lot !
Alexey, normally it have to work fine. Something is wrong with your Apache setup. For example it may have mod_rewrite disabled or something like that.
You have to find the error description in Apache error log or ask hosting support if it’s a shared hosting server.
i want wordpress .htacess desing
Can you explain more?
What do you want to implement and what’s your problem?
At last…a useful explanation that takes you by the hand and that also deals with the relative-url issue. Many thanks.
Greetings from the Netherlands.
You’re welcome, Fred)
Hup Holland hup!
good artile!!!
great article.
But how about multi lang stuff?
Let say first part is language code, if not default language. So I already have 2 different cases.
abc.com/de/aaa/bbb/ccc
1)check if first element is lang code. If so, ignore lang code and use second element as first element and proceed…
2)no lang code set (becasue default language is used) continue like in your example.
Or better language code as last parameter like:
abc.com/aaa/bbb/ccc/ddd?lang=de
what is best for SEO?
I think using virtual folders for languages is better for SEO as search engines may not recognize URL parameters.
can you help me.
i have .htaccess like
RewriteRule ^index.html$ /index.php [QSA]
RewriteRule ^pdf/.* /a-single.php [QSA]
RewriteRule ^ebook/.* /a-single-e.php [QSA]
output:
/pdf/post-title-id.pdf
/ebook/post-title-id.pdf
and i want to change those to
post-title-id.pdf
post-title-id.pdf
help me please
Error if you click on the url of this type with special character site.com/>
Forbidden
You don’t have permission to access /> on this server.
Apache/2.2.23 (Win32) PHP/5.3.18 Server at site.com Port 80
Hi, Yuri!
Perhaps, something like mod_security is blocking it as suspicious URL. I suggest you check server’s error log.
Not relevant to the post’s subject I believe unless I’m missing something.
Hello anton
Thanks for this tutorial, It helps me a lot
But still I am getting confused.. With this
I want urls like this
site.com/mobiles/samsung/galaxy-note/
How can I achieve this
Here in the above url
mobile is main category
samsung is sub category
galaxy note is product
and I want page to be open by category and by subcategory like this
site.com/mobiles
site.com/mobiles/samsung
site.com/mobiles/samsung/galaxy-note
Sir please help me out….
Thanks 🙂
Please read the post carefully, it explains it all. Once you configured .htaccess, you can parse $_SERVER[‘REQUEST_URI’] value in your PHP code. Break it by ‘/’ separator with explode() into say $pathInfo. Then $pathInfo[0] will be your category, $pathInfo[1] – subcategory and $pathInfo[2] will be your product.
Though in the modern PHP world I would recommend using a CMS or framework. The time of custom coding such basic things have definitely passed.
hello sir,
i like the way of your explanation but who are totally newbies like me in htaccess can’t understand it easily so I think you should give a complete example with category and products in zip file to download …..
BTW awesome tutorial 🙂
The post is quite old, dated back to 2009, and many things changed dramatically since it was written. Nowadays I would recommend rather using a PHP framework or CMS.
Anyway, extracting a category and product or whatever you coded into your path structure is just a matter of parsing path string. Sorry, really don’t want to go into that as it’s quite basic matters not related to URL rewriting actually.
hello sir,
hope you are doing well
you explained it very clearly and i learned from it, now i am able to make seo friendly urls in my project ,
but i need your assitance, please help me out
the above commentator @Gautam Nagraj asked you, that exactly i want but in different manner..
i also have category, subcategory, product and product detail page
so i want urls like
php pages are :
——————————
somesite.com/category.php?category_slug=electronics
somesite.com/subcategory.php?subcategory_slug=laptops
somesite.com/product.php?product_slug=lenovo-notebook
i want urls like this
————————————-
somesite.com/electronics
somesite.com/laptops
somesite.com/lenovo-notebook
my htaccess rules are:
——————————————
RewriteRule ^([a-zA-Z0-9-]+)$ category.php?category_slug=$1 [NC,L]
RewriteRule ^([a-zA-Z0-9-]+)$ subcategory.php?subcategory_slug=$1 [NC,L]
RewriteRule ^([a-zA-Z0-9-]+)$ products.php?product_slug=$1 [NC,L]
and i don’t want to show products like this
somesite.com/electronics/laptops/lenovo-notebook
i just want single url for category, subcategory and product
i tried it but it’s working for one file not for all
so please guide me………
Hi, Vikas!
In your case all URLs looks similar to htaccess because you left no way to distinguish one from another. So only the first htaccess rule will always match and the latter two will be ignored as they have identical patterns. Apache have no idea if “notebook” is a category, subcategory or product so you need a way to let it know or move it to the PHP level.
I suggest you either add virtual folders like “category/”, “subcategory/” and “product/” so you can match corresponding URLs by the parent folder name in your htaccess rules. For example, “category/electronics” path will match ^category/(.*) pattern and do not match ^subcategory/(.*) one.
Or, you can use a generic htaccess as listed in the post to route all requests to index.php. There you can match the folder list against available categories, subcategories and products until you find a match. But this will obviously consume more server resources and obviously require you to keep folder names unique. For example, a category “electronics” will take precedence over same named subcategory rendering the latter inaccessible.
Hope that helps.