Upgrade Controllers

Documentations

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.

Upgrade Guide

  1. First, move all controller files to the folder app/Controllers.

  2. Add this line just after the opening php tag: namespace App\Controllers;

  3. Replace extends CI_Controller with extends BaseController.

  4. 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 according to that.
For example, 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 the version 4 should look like this: app/Controllers/Users/Auth/Register.php. Make sure to have the first letters of the sub-directories as capitalized.
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) . '!';
    }
}