Upgrade Controllers¶

Documentation¶

What has been changed¶

Since namespaces have been added to CodeIgniter 4, the controllers must be changed to support namespaces.
The constructor of CI4 Controller does not automatically load core classes into the properties.
CI4's Controller has a special constructor initController().
CI4 provides Request and Responses objects for you to work with - more powerful than the CI3 way.
If you want a base controller (MY_Controller in CI3), use app/Controllers/BaseController.php.
Calling echo within Controllers, as in CI3, is still supported, but it is recommended that a string or Response object be returned from Controllers.

Upgrade Guide¶

First, move all controller files to the folder app/Controllers.
Add this line just after the opening php tag: namespace App\Controllers;
Replace extends CI_Controller with extends BaseController.
Remove the line defined('BASEPATH') OR exit('No direct script access allowed'); if it exists.

If you use sub-directories in your controller structure, you have to change the namespace accordingly.

For example, if you have a version 3 controller located in application/controllers/users/auth/Register.php, the namespace has to be namespace App\Controllers\Users\Auth; and the controller path in version 4 should look like this: app/Controllers/Users/Auth/Register.php. Make sure to capitalize the first letters of the sub-directories.

After that, you have to insert a use statement below the namespace definition in order to extend the BaseController: use App\Controllers\BaseController;

Code Example¶

CodeIgniter Version 3.x¶

Path: application/controllers:

<?php

class Helloworld extends CI_Controller
{
    public function index($name)
    {
        echo 'Hello ' . html_escape($name) . '!';
    }
}

CodeIgniter Version 4.x¶

Path: app/Controllers:

<?php

namespace App\Controllers;

class Helloworld extends BaseController
{
    public function index($name)
    {
        return 'Hello ' . esc($name) . '!';
    }
}