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How To Write a Page Controller in PHP for Dynamic Content February 6, 2010

Posted by chris in : php, seo , trackback

This how to will cover the topic of creating a dynamic content system. It’s a well known fact that when you come across a site like wikipedia that they don’t have an html file for each article. That would be insanity. It would be nearly impossible to display the file tree in an IDE and cumbersome to search through even with an OS that has a slick file system and powerful shell like Linux. Trust me, I worked on a site that created a unique page for each product on their site (they’ve since gotten with the times). So how can web browsers access a page like http://en.wikipedia.org/wiki/Mike_Tyson, when that file doesn’t exist. The application uses a combination of server-side code, database storage, and apache htaccess magic. Here’s how to do this.

Apache HTACCESS
This is the most important part of redirecting dynamic content. The .htaccess file is what makes the magic happen. What happens is a user requests http://en.wikipedia.org/wiki/Mike_Tyson, apache goes to process the request and does its thing. Normally apache would redirect this to a 404 error page because the file does not exist, but if it see’s the .htaccess file in the directory, then apache will follow the rules we defined in the htaccess. Our rule will tell apache that if the file is not found, to go to some other file. We will call this file mycontroller.php (because its the controller in our ModelViewController). Below is some example code to get your started:

Options -Indexes
Options +FollowSymLinks
DirectoryIndex index.php
ErrorDocument 404 /404.php

<IfModule mod_rewrite.c>
  RewriteEngine on
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteCond %{REQUEST_URI} !=/favicon.ico
  RewriteRule ^(.*)$ mycontroller.php [L,QSA]
</IfModule>

Recap:
1. We have /public_html/mydomain.com/wiki/.htaccess
This overwrites the Apache Web Servers default operating procedures.

2. We redirect the request to /public_html/mydomain.com/wiki/mycontroller.php
This contains the server side code that will handle our request for the Mike Tyson article.

The Database
Going in detail on this topic is beyond the scope of this article, but you’ll need some sort of database management system to store your article on Mike Tyson and the thousands of other articles. Of course there are other options like an XML file, but a database such as MySQL is the sanest approach for most sites.

Server Side Code
You’ll need some sort of server-side code running whether is ASP, JSP, or PHP. I’m a bit partial to PHP so lets roll with that. In mycontroller.php your code might look something like this:

$uriArr = explode('/',$_SERVER['REQUEST_URI']);
$article = $uriArr[2];
$article = urldecode($page); // in this case the article equates to Mike_Tyson

$sql = "SELECT * FROM article WHERE name = '$article'";
$result = mysql_query($sql);
if(mysql_num_rows($result) == 1){
	$page = mysql_fetch_assoc($result);
	header('HTTP/1.1 200 OK');
	header('Connection: close');
	include_once 'mytemplatepage.php';
DIE():
}
else{
	header('HTTP/1.1 404 Not Found');
	header('location: /404.php');
	header('Connection: close');
DIE();
}

This is asking our database for any records it has on the request Mike_Tyson. If a row is returned than we know we’ve found our article. We tell the browser that this is a 200 OK request. Then we include a file called mytemplate.php (this file is never actually seen by the browser). We set the record in the database to a variable array called $page. Our mytemplate.php file will look for this variable and begin populating the article. Lets see $page contains the following data: Title, Body, Image, and References. The mytemplate.php file might look something like this:

$title = $page['title '];
$body = $page['body '];
$image = $page['image '];
$references = $page['references '];
echo "<html><head><title>$title</title></head><body>";
echo "<h1>$title</h1>";
echo "<div class="mainImage">$image</div>";
echo "<p>$body</p>";
echo "<p>$references</p>";
echo "</body></html>";

Sweet! We can use the same template for a bunch of different articles, without having to create multiple files. Now if the user had searched for the following url: http://en.wikipedia.org/wiki/Mike_TysonIsEvil, we wouldn’t have an article on that. So instead the code would tell the browser this is a 404 Error and route the browser to the 404.php page.

This is an over simplified version of a dynamic content system, but it would work. If I was developing one of these on a professional level it would be complete with objects to handle requests, string cleaners to protect against SQL injection and XSS attacks, error logging, and the works! Let me know if you have questions I can answer and thanks for reading.

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