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In technology, there’s always the goal of making complex and difficult things more simple - this goal has brought about ‘clean URLs’. Clean URLs are website addresses that are easy for people (and also search engines) to read and understand. For example: An interesting article about the Bermuda Triangle might be at www.articles.com/article.php?id=23452 - That address tells us (and search engines) nothing about the article. Using a clean URL, the same article might be at www.articles.com/articles/bermuda-triangle - much easier, right? Well, here is how you can implement this on your website…

Setting Up Apache’s “mod_rewrite” Modul

To implement these URLs with Apache, you will need to have the mod_rewrite module enabled. Here’s how to enable mod_rewrite:

1. Open the httpd.conf file from the …apache/conf/ directory
2. Uncomment the line “LoadModule rewrite_module modules/mod_rewrite.so” (by removing preceding #)

If you have more than one virtual server or directory set up, you might have to add something like this as well:

<Directory "PATHOFDIRECTORY">
    AllowOverride all
    Order allow,deny
    Allow from all
</Directory>

Next, you need to create a file named “.htaccess” at the website’s root directory (if you haven’t got one already)

In your .htaccess file, add the following rules:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

This will redirect all requests that don’t point to an existing file or directory to ‘index.php’.

You might (or might not) be thinking “How does that help implement clean URLs?” The next part will answer that question, but before proceeding - test your new Apache config and .htaccess file - restart Apache if necessary and try loading a directory that doesn’t exist (ie. http://yourwebsitehost/page/5/your-information/). If it loads your index.php page - we’re ready to continue.

Getting PHP to Interpret The URLs

Ok, the hard part is done. Now I’ll explain what we want when a user requests a page:

1. User requests “/page/5/your-information/”
2. Apache redirects the request to “index.php” without changing the user’s URL
3. index.php breaks up the requet URI and loads page.php instructing it to load page ‘5′

This might seem a bit difficult (or, if you’re experienced, very easy) - it honestly is rather easy. Once you understand how it works, you might decide to do it differently, but here is a really simple example of a website that contains information ‘pages’ and information about the ‘authors’ of those pages.

In our example, we have three php files:

• index.php
• page.php
• author.php

“index.php”

<?php
//$urlVariables is an array that contains the different bits of information in the request.
$urlVariables = explode("/",$_SERVER['REQUEST_URI']);
//If the user requested '/page/6/about-elephans/' then $urlVariables[1] would be 'page', $urlVariables[2] would be '6' and so on.

if ($urlVariables[1] == "page") {
//the user is requesting an information page
    include "page.php";
} elseif $urlVariables[2] == "author" {
    //the user is requesting author information
    include "author.php";
} else {
    //load the home page
    include "default.php";
}?>

“page.php”

<?php//load an object that deals with pages (to keep the tutorial simple)
include "classes/page.php";
$page = new page;
//$urlVariables will contain the page id as the 2nd array element (ie. /page/pageid/page-name-here/)$page_id = $urlVariables[2];
//the page name part of the URL is ignored when loading because we only use ID to load pages - it's just good for search engines and people.

//get the page class to load the page
if ($page->load_page($page_id)) {?>

<h1><?php echo $page->page_name(); ?></h1>
<p><?php echo $page->page_content(); ?></p>
<p>Written by <a href="<?php echo $page->author_url(); ?>"> <?php echo $page->author_name(); ?> </a></p><?php

} else {

    //error!
    include "error.php";
}>

“about.php”

<?php

//load an object that deals with authors (again, to keep the tutorial simple)
include "classes/author.php";
$author = new author;
//$urlVariables will contain the page id as the 2nd array element (ie. /author/authorid/author-name-here/)
$author_id = $urlVariables[2];
//again, the author name part of the URL is ignored when loading because we also only use ID to load authors - it is just good for search engines and people.

//get the author class to load the page
if ($author->load_author($author_id)) {?>
<h1><?php echo $author->author_name(); ?></h1>
<h2>Bio</h2><p><?php echo $author->author_information(); ?></p>
<h2>All pages by <?php echo $author->author_name; ?></h2>
<$php echo $author->page_list; 

} else {
    //error!
    include "error.php";
}
?>

Now that example was probably a bit excessive. Here’s a basic overview of how it works:

1. The index.php page is loaded, and ‘explodes’ the request part of the URL into an array ($urlVariables in the example)
2. You then interpret the array elements to decide what to show to the user. ($urlVariables[1] determined whether to show a page or an author profile and $urlVariables[2] was an ID for either the page or the author in our example)

It’s that simple. This method is SUPER flexible if you build a strong framework around it.

Good luck!

This entry was posted on Sunday, February 10th, 2008 at 3:39 pm and is filed under PHP, SEO, Web Design. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.