Key Architecture Takeaways

• ›
  Point 1: Full-stack architecture blueprint: CodeIgniter Creating Extending Replacing Libraries.
• ›
  Point 2: Covers MVC separation of concerns, routing pipelines, and database abstraction.
• ›
  Point 3: Modern ecosystems: Laravel 11/PHP 8.3, React 19, and Node.js LTS runtimes.

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Creating your own libraries:

You can easily create your own libraries. The first step in creating a library is to create a file inside the *System/application/libraries/* directory, with a relevant name, you should also take the naming conventions outlined in the style guide into account. The next step is to create a class inside this file, with the same name as your PHP file, but without the .php extension. You do not need to extend any classes when creating your own library.

<blockquote>While creating new library one should keep in mind, the following things −

- The name of the file must start with a capital letter e.g. Example_library.php - class name must start with a capital letter e.g. class Example_library - The name of the class and name of the file must match.

</blockquote>

A prototype of "Example_library.php"

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
 
 class Example_library {

 
       public function some_function() {

       //your function body
       //......

      }
 }
 
/* End of file Example_library.php */

Utilizing CodeIgniter Resources within Your Library:

When using CodeIgniter, you load helpers, libraries, and other resources by using the super object $this->. However, when creating your own library, you will not have access to this unless you explicitly add it in by using the following function: $CI =& get_instance();

Once you do this inside a function, you would use $CI in place of $this when utilizing CodeIgniter resources.

class Example_library {

 protected $CI;

 // We'll use a constructor, as you can't directly call a function
 // from a property definition.
 public function __construct()
 {
      // Assign the CodeIgniter super-object
      $this->CI =& get_instance();
 }

 public function foo()
 {
     $this->CI->load->helper('url');
     redirect();
 }

 public function bar()
 {
     echo $this->CI->config->item('base_url');
 }

}

Use your own Class:

You can simply load your library using load method in your application. for example

$this->load->library('example_library');

Extending core libraries:

To extend a core CodeIgniter library, first, create a file with the same name as the library you wish to extend, but add the MY_ prefix. For example, to extend the Session class, create a file called MY_Session.php and place it inside the *system/application/libraries *directory. Once this is done, you simply extend the core library as follows:

<?php  class MY_Session extends CI_Session{

    function MY_Session()
    {
        parent::CI_Session();
    }
 }
?>

Loading Extending Libraries:

You load your extended library in exactly the same way as you load the core library.

$this->load->library('session');

Note that I do not include the MY_ prefix to load my extended library. There is no need to include the prefix at the time of loading.

Replacing core libraries:

Replacing core libraries is similar to extending them. Instead of using the MY_ prefix in your file name and class name, you drop the prefix for the filename and use the prefix CI_ for the class name. This is because all CodeIgniter core libraries have the prefix CI_. Staying with the session class, we would replace it as follows:

<?php class CI_Session{

// Your updated class..

}
?>

Loading Replaced Library:

Loading method is similar as extending library.

$this->load->library('session');

Conclusion:

So you can create your own library for your application, and also customize any existing library as you wish in CodeIgniter with flexible way.