CodeIgniter Features : CodeIgniter User Guide
Author: ExpressionEngine Dev Team
Description: CodeIgniter User Guide

# CodeIgniter User Guide Version 2.2.1

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# Tutorial − Static pages

Note: This tutorial assumes you've downloaded CodeIgniter and installed the framework in your development environment.

The first thing you're going to do is set up a controller to handle static pages. A controller is simply a class that helps delegate work. It is the glue of your web application.

For example, when a call is made to: `http://example.com/news/latest/10` We might imagine that there is a controller named "news". The method being called on news would be "latest". The news method's job could be to grab 10 news items, and render them on the page. Very often in MVC, you'll see URL patterns that match: `http://example.com/[controller-class]/[controller-method]/[arguments]` As URL schemes become more complex, this may change. But for now, this is all we will need to know.

Create a file at application/controllers/pages.php with the following code.

<?php class Pages extends CI_Controller { public function view($page = 'home') { } }

You have created a class named "pages", with a view method that accepts one argument named $page. The pages class is extending the CI_Controller class. This means that the new pages class can access the methods and variables defined in the CI_Controller class (system/core/Controller.php).

The controller is what will become the center of every request to your web application. In very technical CodeIgniter discussions, it may be referred to as the super object. Like any php class, you refer to it within your controllers as $this. Referring to $this is how you will load libraries, views, and generally command the framework.

Now you've created your first method, it's time to make some basic page templates. We will be creating two "views" (page templates) that act as our page footer and header.

Create the header at application/views/templates/header.php and add the following code.

<html> <head> <title><?php echo $title ?> - CodeIgniter 2 Tutorial</title> </head> <body> <h1>CodeIgniter 2 Tutorial</h1>

The header contains the basic HTML code that you'll want to display before loading the main view, together with a heading. It will also output the $title variable, which we'll define later in the controller. Now create a footer at application/views/templates/footer.php that includes the following code:

<strong>&copy; 2011</strong> </body> </html>

## Adding logic to the controller

Earlier you set up a controller with a view() method. The method accepts one parameter, which is the name of the page to be loaded. The static page templates will be located in the application/views/pages/ directory.

In that directory, create two files named home.php and about.php. Within those files, type some text − anything you'd like − and save them. If you like to be particularly un-original, try "Hello World!".

In order to load those pages, you'll have to check whether the requested page actually exists:

    public function view($page = 'home')
    {

    	if ( ! file_exists(APPPATH.'/views/pages/'.$page.'.php'))
    	{
    		// Whoops, we don't have a page for that!
    		show_404();
    	}

    	$data['title'] = ucfirst($page); // Capitalize the first letter

    	$this->load->view('templates/header', $data);
    	$this->load->view('pages/'.$page, $data);
    	$this->load->view('templates/footer', $data);

    }

Now, when the page does exist, it is loaded, including the header and footer, and displayed to the user. If the page doesn't exist, a "404 Page not found" error is shown.

The first line in this method checks whether the page actually exists. PHP's native file_exists() function is used to check whether the file is where it's expected to be. show_404() is a built-in CodeIgniter function that renders the default error page.

In the header template, the $title variable was used to customize the page title. The value of title is defined in this method, but instead of assigning the value to a variable, it is assigned to the title element in the $data array.

The last thing that has to be done is loading the views in the order they should be displayed. The second parameter in the view() method is used to pass values to the view. Each value in the $data array is assigned to a variable with the name of its key. So the value of $data['title'] in the controller is equivalent to $title in the view.

## Routing

The controller is now functioning! Point your browser to [your-site-url]index.php/pages/view to see your page. When you visit index.php/pages/view/about you'll see the about page, again including the header and footer.

Using custom routing rules, you have the power to map any URI to any controller and method, and break free from the normal convention: `http://example.com/[controller-class]/[controller-method]/[arguments]`

Let's do that. Open the routing file located at application/config/routes.php and add the following two lines. Remove all other code that sets any element in the $route array.

    $route['default_controller'] = 'pages/view';
    $route['(:any)'] = 'pages/view/$1';

CodeIgniter reads its routing rules from top to bottom and routes the request to the first matching rule. Each rule is a regular expression (left-side) mapped to a controller and method name separated by slashes (right-side). When a request comes in, CodeIgniter looks for the first match, and calls the appropriate controller and method, possibly with arguments.

More information about routing can be found in the URI Routing documentation.

Here, the second rule in the $routes array matches any request using the wildcard string (:any). and passes the parameter to the view() method of the pages class.

Now visit index.php/about. Did it get routed correctly to the view() method in the pages controller? Awesome!