CodeIgniter 3 User Guide

CodeIgniter is a PHP application development framework designed to accelerate web development by providing a rich set of libraries for common tasks, a simple interface, and a logical structure.

Note on Versioning: This repository contains CodeIgniter 3, which is the legacy version of the framework. It is intended for use with PHP 5.6+ and is currently in maintenance mode, receiving primarily security updates. For the latest version, use CodeIgniter 4.

The Session class allows you to maintain a user's 'state' and track their activity throughout their browsing session. CodeIgniter provides several built-in storage drivers to handle session data, which can be configured based on your application's needs.

Supported storage drivers include:

• files: The default driver, which uses the local file system.
• database: Stores session data in a database table.
• redis: Uses a Redis server for high-performance storage.
• memcached: Uses Memcached for distributed memory caching.

You can also implement custom session drivers to use alternative storage mechanisms while still utilizing the core features of the Session class.

CodeIgniter provides two primary classes for XML-RPC communication:

1. XML-RPC Client: Used to send requests to a remote server.
2. XML-RPC Server: Used to set up your own server to receive and process incoming XML-RPC requests.

XML-RPC is a protocol that allows two computers to communicate over the internet using XML. The client sends an XML-RPC request, and the server responds with an XML-RPC response after processing the request.

CodeIgniter provides a comprehensive form validation and data prepping class designed to minimize the boilerplate code required for handling user input. The library automates the lifecycle of form submission, including:

1. Data Verification: Checking for required fields and ensuring data meets specific criteria (type, length, character sets, uniqueness, etc.).
2. Security & Sanitization: Cleaning data to prevent common vulnerabilities.
3. Data Prepping: Formatting data (e.g., trimming, HTML encoding) and preparing it for database insertion.
4. Error Handling: Managing the redisplay of forms with error messages and preserving user input when validation fails.

The Loader class is the central mechanism for loading various application elements, including:

• Libraries (classes)
• View files
• Drivers
• Helpers
• Models
• Custom files

Note that the Loader class is initialized automatically by the system; you do not need to instantiate it manually.

Models are PHP classes designed to manage information in your database. They are used to implement a traditional MVC (Model-View-Controller) approach, housing functions for inserting, updating, and retrieving data. Models should extend the base CI_Model class.

class Blog_model extends CI_Model {

	public $title;
	public $content;
	public $date;

	public function get_last_ten_entries()
	{
		$query = $this->db->get('entries', 10);
		return $query->result();
	}

	public function insert_entry()
	{
		$this->title = $_POST['title'];
		$this->content = $_POST['content'];
		$this->date = time();

		$this->db->insert('entries', $this);
	}

	public function update_entry()
	{
		$this->title = $_POST['title'];
		$this->content = $_POST['content'];
		$this->date = time();

		$this->db->update('entries', $this, array('id' => $_POST['id']));
	}
}

To prevent certain methods from being accessible via a URL request, declare them as private or protected.

Additionally, prefixing a method name with an underscore (_) will also prevent it from being called via URL (this is a legacy compatibility feature).

class Blog extends CI_Controller {

    // This cannot be accessed via example.com/index.php/blog/_utility/
    private function _utility()
    {
        // some code
    }
}

When sending requests, parameters can be sent as a simple array of values (if they are all strings). However, if you need to use specific XML-RPC data types (like int, boolean, or struct), you must wrap each parameter in its own array where the second element is the type name.

Example of mixed data types:

$request = array(
    array('John', 'string'),
    array('Doe', 'string'),
    array(FALSE, 'boolean'),
    array(12345, 'int')
);
$this->xmlrpc->request($request);

The Output class is a core component responsible for sending the finalized web page to the browser and managing page caching.

It is initialized automatically by the system. Under normal circumstances, it works transparently: when you use the Loader class to load a view, the content is automatically passed to the Output class and sent to the browser at the end of the system execution. However, developers can manually intervene to set specific content types, headers, or status codes.