A Content Management System ( CMS ) is used to add, edit, and delete content on a website. For a small website, such as this, adding and deleting a page manually is fairly simple. But for a large website with lots of pages like a news website adding a page manually without a content management system can be a headache.
A CMS is meant to ease the process of adding and modifying new content to a webpage. The pages content are stored in database, not in the file server.
This tutorial will present an example of a simple content management system. You will be able to add, edit and delete articles using HTML forms.
For the database table we'll call it the news table. It consist of three columns :
- id : The article's id
- title : The title of an article
- content : The article itself
Now that we have the script to add articles let's create another script to view those articles. The script is list the title of articles available in database as clickable links. The article link have the article id appended like this http://www.php-mysql-tutorial.com/examples/cms/article1.php?id=3 One possible implementation of article1.php is presented below : |
With this implementation each article request involve one database query. For a heavy load website with lots of articles using the above implementation can cause a very high amount of database-request. So we need a better cms solution to reduce the load. Example : |
First we need to specify the cache directory where all cache files are located. For this example the cache directory is located in the same place as the article2.php script. I mean if article2.php is stored in C:/webroot then the cache dir is in C:/webroot/cache/
The script thent check if the article was already in the cache. An article is saved into the cache directory using a filename generated from it's id. For example if you request the article using a link like this :
Then the cache file for the article is_3.html
This filename is just an underscore ( _ ) followed by the article id. In case article2.php is called like this :
no id is defined so we make the cache file name as index.html
If the cache file is found , the content is read and printed using readfile() and the script terminate. When the article is not found in the cache then we need to look in the database and get the page content from there.
Example :
<?php
// ... previous code
if(!isset($_GET['id']))
{
$self = $_SERVER['PHP_SELF'];
$query = "SELECT id, title FROM news ORDER BY id";
$result = mysql_query($query) or die('Error : ' . mysql_error());
$content = '<ol>';
while($row = mysql_fetch_array($result, MYSQL_NUM))
{
list($id, $title) = $row;
$content .= "<li><a href=\"$self?id=$id\">$title</a></li>\r\n";
}
$content .= '</ol>';
$title = 'Available Articles';
} else {
// get the article info from database
$query = "SELECT title, content FROM news WHERE id=".$_GET['id'];
$result = mysql_query($query) or die('Error : ' . mysql_error());
$row = mysql_fetch_array($result, MYSQL_ASSOC);
$title = $row['title'];
$content = $row['content'];
}
include 'library/closedb.php';
// ... still more code coming
?>
As you can see above the process of fetching the article list and content is the same as article1.php. But before showing the page we have to start output buffering so we can save the content of the generated HTML file.
See the code below. Just before printing the html we callob_start() to activate output buffering. From this point no output is sent from the script to the browser. So in the code example below anything between <html> and </html> tag is not sent to the browser but stored in an internal buffer first.
After the closing html tag we useob_get_contents() to get the buffer content and store int in a temporary variable, $buffer. We then call ob_end_flush() which stop the output buffering ( so the page is now sent to the browser ).
Example :
<?php
// ... previous code
ob_start();
?>
<html>
// ... same html code as article1.php
</html>
<?php
// get the buffer
$buffer = ob_get_contents();
// end output buffering, the buffer content
// is sent to the client
ob_end_flush();
// now we create the cache file
$fp = fopen($cacheFile, "w");
fwrite($fp, $buffer);
fclose($fp);
?>
Now that we have the file content we can write the cache file using the filename generated earlier ( using underscore plus the article id ). From now on any request to the article will no longer involve a database query. At least until the article is updated.
