+ +
+

Creating Core System Classes

+

Every time CodeIgniter runs there are several base classes that are +initialized automatically as part of the core framework. It is possible, +however, to swap any of the core system classes with your own versions +or even extend the core versions.

+

Most users will never have any need to do this, but the option to +replace or extend them does exist for those who would like to +significantly alter the CodeIgniter core.

+
+

Note

+

Messing with a core system class has a lot of implications, so +make sure you know what you are doing before attempting it.

+
+
+

System Class List

+

The following is a list of the core system files that are invoked every +time CodeIgniter runs:

+
    +
  • Benchmark
    • +
  • Config
    • +
  • Controller
    • +
  • Exceptions
    • +
  • Hooks
    • +
  • Input
    • +
  • Language
    • +
  • Loader
    • +
  • Log
    • +
  • Output
    • +
  • Router
    • +
  • Security
    • +
  • URI
    • +
  • Utf8
    • +
+
+
+

Replacing Core Classes

+

To use one of your own system classes instead of a default one simply +place your version inside your local application/core/ directory:

+
application/core/some_class.php
+
+
+

If this directory does not exist you can create it.

+

Any file named identically to one from the list above will be used +instead of the one normally used.

+

Please note that your class must use CI as a prefix. For example, if +your file is named Input.php the class will be named:

+
class CI_Input {
+
+}
+
+
+
+
+

Extending Core Class

+

If all you need to do is add some functionality to an existing library - +perhaps add a method or two - then it’s overkill to replace the entire +library with your version. In this case it’s better to simply extend the +class. Extending a class is nearly identical to replacing a class with a +couple exceptions:

+
    +
  • The class declaration must extend the parent class.
    • +
  • Your new class name and filename must be prefixed with MY_ (this +item is configurable. See below.).
    • +
+

For example, to extend the native Input class you’ll create a file named +application/core/MY_Input.php, and declare your class with:

+
class MY_Input extends CI_Input {
+
+}
+
+
+
+

Note

+

If you need to use a constructor in your class make sure you +extend the parent constructor:

+
class MY_Input extends CI_Input {
+
+        public function __construct()
+        {
+                parent::__construct();
+                // Your own constructor code
+        }
+}
+
+
+
+

Tip: Any functions in your class that are named identically to the +methods in the parent class will be used instead of the native ones +(this is known as “method overriding”). This allows you to substantially +alter the CodeIgniter core.

+

If you are extending the Controller core class, then be sure to extend +your new class in your application controller’s constructors.

+
class Welcome extends MY_Controller {
+
+        public function index()
+        {
+                $this->load->view('welcome_message');
+        }
+}
+
+
+
+

Setting Your Own Prefix

+

To set your own sub-class prefix, open your +application/config/config.php file and look for this item:

+
$config['subclass_prefix'] = 'MY_';
+
+
+

Please note that all native CodeIgniter libraries are prefixed +with CI_ so DO NOT use that as your prefix.

+
+
+
+ + +