Dynamically generating page links for a CMS - php

Question

I've searched far and wide and every CMS tutorial out there either doesn't explain this at all or gives you a huge chunk of code without explaining how it works. Even on stack overflow I can't find anything close to the answer, though I'd be okay with eating my words if someone could point me to the answer.
I am using PHP and mysql for this project.
I am building a CMS. Its extremely simple and I understand every concept I think I'll need except how to dynamically generate pages and page links. The way I want to do it is by having a database table that stores the name of a page and the main content of the page. That's all. Then I'd just call a script to pull the main content of a page into whatever page I happen to call. No big deal, right? Wrong.
Here's the problem. If I were to do this then I'd have to create a file for every page I want to create that calls the script that pulls the content from the correct database row. So I could add all sorts of page names and contents into the table but I don't know how to call them without manually creating new files each time I want to link to a new page.
Ideally there'd be a script that creates links to pages based on the page name row of the DB table as the pages are created. But how do you get those links with the ?=pageName at the end? If I just knew how that worked then I could figure the rest out.
UPDATE
The second answer really confirmed everything I thought I had to do but there is one catch. My plan now is to split up all the code into a series of functions and either include or require them in different templates that will be used to format the way pages are displayed. I need one look for the home page and one other design for the rest of the pages. I'm thinking that I'll have a function that says if ID is 0 then call this page template.php else call this other template file.php. But how do I pass the required variables to these new files? Do I just include the index.PHP page in them?

Answer 1

Bill your actually on the right track. Almost all web software today does extensive URL processing. Traditionally you would have php pages on your web root and then utilize the query string in the URL to refine the page's output. You have already arrived at why this might not be desired. So the popular alternative is the Front Controller design pattern. Basically we funnel every request to your index.php page and then route the request to internal pages or apps outside the web root. This can get complicated fast and everybody seems to implement this pattern in unique ways.
We can utilize this pattern without the routing by simply putting our app in the index page. The script below shows an example of what your trying to do in the simplest of ways. We basically have one page with our script. We can request the virtual pages by changing the id query string in our url. For example www.demo.net/?id=0 can be utilized as an index to your site. This should be the same as www.demo.net without the 'id' query. Just keep solving those problems one by one even if you don't know what the problem is. Once you start looking at other peoples code, then you can start seeing how other people solved the same problems you have.
The solution below will get you started, but then what do you do when you want an admin page? How do you authenticate the user? Do you duplicate alot of the code for yet another page? If your serious about your CMS then your going to want to implement some kind of framework underneath it. A framework to process the url, route to your application, load configuration files, and probably manage your database connection. Yea it gets complicated, but not if you solve each problem one at a time. Utilize classes or functions to share code to start. At the very least include a common "bootstrap" file at the top of your page to initialize common functionality such as a database connection. Read Stack Overflow just to keep up with whats going on. You can learn alot of terminology and probably find some answers to questions you didn't even know you wanted to ask.
Below assume we have a table with the following fields:
page_id
page_name
page_title
page_body
<?php
//<--------Move outside of web root-------------->
define('DB_HOST', 'localhost');
define('DB_USER', 'cms');
define('DB_PASS', 'changeme');
define('DB_DB', 'cms');
define('DB_TABLE', 'cms_pages');
//<---------------------------------------------->
//Display errors for development testing
ini_set('display_errors','On');
//Get the requested page id
if(isset($_GET['id']))
{
$id = $_GET['id'];
}
else
{
//Make page id '0' an index page to catch all
$id = 0;
}
//Establish a connection to MySQL
$conn = mysql_connect(DB_HOST,DB_USER,DB_PASS) or die(mysql_error());
//Select the database we will be querying
mysql_select_db(DB_DB, $conn) or die(mysql_error());
//Lets just grab the whole table
$sql = "SELECT * FROM ".DB_TABLE;
$resultset = mysql_query($sql, $conn) or die(mysql_error());
//The Select Query succeeded, but returned 0 result.
if (mysql_num_rows($resultset)==0)
{
echo "<pre>Add some Pages to my CMS</pre>";
exit;
}
//This is our target array we need to fill with arrays of pages
$result = array();
//Convert result into an array of associative arrays
while($row = mysql_fetch_assoc($resultset))
{
$result[] = $row;
}
//We now have all the information needed to build our app
//Page name - Short name for buttons, etc.
$name = "";
//Page title - The page content title
$title = "";
//Page body - The content you have stored in a table
$body = "";
//Page navigation - Array of formatted links
$nav = array();
//Process all pages in one pass
foreach($result as $row)
{
//Logic to match the requested page id
if($row['page_id'] == $id)
{
//Requested Page
$name = $row['page_name'];
$title = $row['page_title'];
$body = $row['page_body'];
$page = "<b>$name</b>";
}
else
{
//Not the requested page
$page = $row['page_name'];
}
//Build the navigation array preformatted with list items
$url = "./?id=" . $row['page_id'];
$nav[] = "<li>$page</li>";
}
?>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>SimpleCMS | <?php echo $title; ?></title>
</head>
<body>
<div>
<div id="navigation" style="float:left;">
<ul>
<?php
foreach($nav as $item)
{
echo $item;
}
?>
</ul>
</div>
<div id="content"><?php echo $body;?></div>
</div>
</body>
</html>

Answer 2

I think you need to read about $_GET.
I also recommend a decent PHP book. Forget online tutorials; they are (for the most part) utterly useless.