HowToUpgradeFromCI3ToCI4.md

How to Upgrade from CI3 to CI4

Table of Contents

• Read CodeIgniter4 User Guide
• Install CodeIgniter4
• Install ci3-to-4-upgrade-helper
• Config
  • config.php
  • Routing
  • autoload.php
  • Custom Config Files
  • Other Config Files
  • app/Config/View.php
• Hooks
• Database Migrations
  • Copy Migration files
  • Add Namespace and Use statement
  • $this->db
  • Table migrations
• Database Seeding
  • Copy Seeder files
  • Add Namespace and Use statement
  • $this->db
  • $this->call()
• Controllers
  • Copy Controller files
  • Add Namespace and Use statement
  • _output()
  • MY_Controller
• Models
  • Copy Model files
  • Add Namespace and Use statement
• Libraries
  • Copy Library files
  • Add Namespace
  • Form_validation
    • Validation Rules
  • Pagination
• Views
  • Copy View files
• Helpers
  • Copy Helper files
  • URL Helper
    • redirect()
    • base_url()
    • url_title()
• Common Functions
  • show_error()
• Language files
• Writable Paths

Read CodeIgniter4 User Guide

CodeIgniter 4 is a rewrite of the framework. It is not an exaggeration to say that it is a new framework. Please read the User Guide carefully to get an overview.

• Upgrading from 3.x to 4.x
• CodeIgniter4 Overview
• General Topics

Install CodeIgniter4

See https://codeigniter4.github.io/CodeIgniter4/installation/index.html.

Note Use 4.3.1 or later. ci4-app-template can be used.

Install ci3-to-4-upgrade-helper

$ composer require kenjis/ci3-to-4-upgrade-helper:1.x-dev

Config

config.php

1. Migrate application/config/config.php to app/Config/App.php manually. You can set your own values like base_url with .env file.

Routing

1. Migrate application/config/routes.php to app/Config/Routes.php manually.

See https://codeigniter4.github.io/CodeIgniter4/incoming/routing.html#setting-your-own-routing-rules.

autoload.php

1. CI4 does not have CI3's “Auto-load” feature, except helper autoloading.
2. To autoload helpers, add your $autoload['helper'] value in autoload.php config to the property $helpers in app/Config/Autoload.php. This is CI4's feature.
3. To autoload libraries, add your autoload.php config in the property $libraries in app/Controllers/BaseController.php. This feature is provided by ci3-to-4-upgrade-helper.

Example:

--- a/app/Controllers/BaseController.php
+++ b/app/Controllers/BaseController.php
@@ -20,6 +20,17 @@ use Psr\Log\LoggerInterface;
 
 class BaseController extends Controller
 {
+    /**
+     * CI3's $autoload['libraries']
+     *
+     * @var array
+     */
+    protected $libraries = [
+        'database',
+        'session',
+        'form_validation',
+    ];
+
     /**
      * An array of helpers to be loaded automatically upon
      * class instantiation. These helpers will be available

Custom Config Files

1. Convert custom config files to Config classes manually.

See https://codeigniter4.github.io/CodeIgniter4/general/configuration.html#creating-configuration-files.

2. Replace the CI3 config name with the new config classname in your code.

Example:

$this->config->load('config_shop');

↓

$this->config->load('ConfigShop');

Other Config Files

1. Migrate remaining application/config/*.php to app/Config/*.php manually. You can set your own values like database password with .env file.

app/Config/View.php

1. If you use $this->config in view files, you need to add the following code.

--- a/app/Config/View.php
+++ b/app/Config/View.php
@@ -3,9 +3,12 @@
 namespace Config;
 
 use CodeIgniter\Config\View as BaseView;
+use Kenjis\CI3Compatible\Traits\View\ThisConfigInView;
 
 class View extends BaseView
 {
+   use ThisConfigInView;
+
    /**
     * When false, the view method will clear the data between each
     * call. This keeps your data safe and ensures there is no accidental

Hooks

1. Migrate application/config/hooks.php to app/Config/Events.php or app/Config/Filters.php manually.
2. Migrate application/hooks/* to Events or Controller Filters manually.

See https://codeigniter4.github.io/CodeIgniter4/extending/events.html or https://codeigniter4.github.io/CodeIgniter4/incoming/filters.html.

Database Migrations

CI4 has built-in Database Migrations. ci3-to-4-upgrade-helper provides CI_Migration class that extends CI4's Migration class.

Copy Migration files

1. Copy migration files to app/Database/Migrations/.
2. Rename migration file names. See https://codeigniter4.github.io/CodeIgniter4/dbmgmt/migration.html#migration-file-names.
3. Rename migration class names. Remove Migration_ and change to CamelCase.

Add Namespace and Use statement

1. Add namespace App\Database\Migrations.
2. Add use Kenjis\CI3Compatible\Library\CI_Migration;

Example:

namespace App\Database\Migrations; // Add

use Kenjis\CI3Compatible\Library\CI_Migration; // Add

class CreateBbs extends CI_Migration
{
    ...
}

$this->db

$this->db in migration files is CI4's Database connection. If you want to use CI3 compatible $this->db, replace it with $this->db_ which ci3-to-4-upgrade-helper provides.

Table migrations

The table migrations in CI3 is incompatible. The definition of the table for CI4 MySQL is:

create table migrations
(
    id        bigint unsigned auto_increment primary key,
    version   varchar(255)     not null,
    class     varchar(255)     not null,
    `group`   varchar(255)     not null,
    namespace varchar(255)     not null,
    time      int              not null,
    batch     int(11) unsigned not null
)
    charset = utf8;

If you want to use the database you have been using in CI3:

1. You must drop (or rename) the table migrations.
2. Create a new table migrations for CI4.
3. Run the CI4 migration in the development environment or so, to create the migration data.
4. Import the new migration data of CI4 into your production migrations table.

Database Seeding

CI4 has built-in Database Seeding. ci3-to-4-upgrade-helper provides Seeder class that is based on Seeder class in ci-phpunit-test and extends CI4's Seeder class.

Copy Seeder files

1. Copy seeder files to app/Database/Seeds/.

Add Namespace and Use statement

1. Add namespace App\Database\Seeds.
2. Add use Kenjis\CI3Compatible\Library\Seeder;

Example:

namespace App\Database\Seeds; // Add

use Kenjis\CI3Compatible\Library\Seeder; // Add

class ProductSeeder extends Seeder
{
    ...
}

$this->db

$this->db in seeder files is CI4's Database connection. If you want to use CI3 compatible $this->db, replace it with $this->db_ which ci3-to-4-upgrade-helper provides.

$this->call()

$this->call() in seeder files is the method of CI4's Seeder. If you want to use ci-phpunit-test compatible $this->call(), replace it with $this->call_().

Controllers

Copy Controller files

1. Copy application/controllers/* to app/Controllers/*.
2. Rename the sub-folder names so that only the first letter is uppercase.

Add Namespace and Use statement

1. Add namespace App\Controllers;.
2. Add use Kenjis\CI3Compatible\Core\CI_Controller;

Example:

namespace App\Controllers; // Add

use Kenjis\CI3Compatible\Core\CI_Controller; // Add

class News extends CI_Controller
{
    ...
}

_output()

1. CI4 does not have _output() method.

• Use Controller Filters. See https://codeigniter4.github.io/CodeIgniter4/incoming/filters.html.

MY_Controller

1. Copy application/core/MY_Controller to app/Controllers/MY_Controller.
2. Add Namespace and Use statement as other controllers.

Models

Copy Model files

1. Copy application/models/* to app/Models/*.
2. Rename the sub-folder names so that only the first letter is uppercase.

Add Namespace and Use statement

1. Add namespace App\Models;.
2. Add use Kenjis\CI3Compatible\Core\CI_Model;

Example:

namespace App\Models; // Add

use Kenjis\CI3Compatible\Core\CI_Model; // Add

class News_model extends CI_Model
{
   ...
}

Libraries

Copy Library files

1. Copy application/libraries/* to app/Libraries/*.
2. Rename the sub-folder names so that only the first letter is uppercase.

Add Namespace

1. Add namespace App\Libraries;.

Example:

namespace App\Libraries; // Add

class Seeder
{
   ...
}

Form_validation

1. CI4 has View templates to display errors.

• The CI3 methods to customize error output are not supported.
• Create your own templates, and configure it in app/Config/Validation.php.
• See https://codeigniter4.github.io/CodeIgniter4/libraries/validation.html#customizing-error-display.
• error_string() is also not supported. Use error_array() instead, if you really need it.

Example:

array_reduce($this->form_validation->error_array(), function ($carry, $item) {
    $carry .= '<p>'.$item.'</p>';
    return $carry;
});

• If you need more than one template for list or single, please use CI4's native methods and pass your template name.

Examples:

<?= \Config\Services::validation()->listErrors('my_list') ?>

<?= \Config\Services::validation()->showError('username', 'my_single') ?>

2. CI4 has no Callbacks nor Callable.

• But you can create a validation rule with Closure.
• Or Create your own Rule classes, and configure it in app/Config/Validation.php. See https://codeigniter4.github.io/CodeIgniter4/libraries/validation.html#creating-custom-rules.

3. set_message()

• If you create a custom rule, use the second param &$error and set the error message. See https://codeigniter4.github.io/CodeIgniter4/libraries/validation.html#creating-custom-rules.
• Otherwise, use CI_Form_validation::setError(string $field, string $error) that ci3-to-4-upgrade-helper provides.

4. CI4's Validation never changes your data.

• If you set the rule trim|required, the value during validation is trimmed, but the value after validation is not trimmed. You must trim it by yourself.

Validation Rules

1. Setting validation rules providing a constructor param array is not supported. Please convert it to Config\Validation class. See https://codeigniter4.github.io/CodeIgniter4/libraries/validation.html#saving-sets-of-validation-rules-to-the-config-file.
2. CI4's format rules like alpha_numeric, valid_email do not permit empty string. If you want to permit empty, add the rule permit_empty.

Pagination

1. CI4 has View templates for Pagination.

• The CI3 configurations to customize pagination links are not supported.
• Create your own templates, and configure it in app/Config/Pager.php.
• Use $pager->hasNextPage() and $pager->getNextPage() instead of $pager->hasNext() $pager->getNext() for the next page link.
• A sample file is included in src/CI3Compatible/Views/Pager/. You could use it.

app/Config/Pager.php

    public $templates = [
        'default_full'   => 'Kenjis\CI3Compatible\Views\Pager\default_full',
        'default_simple' => 'CodeIgniter\Pager\Views\default_simple',
        'default_head'   => 'CodeIgniter\Pager\Views\default_head',
    ];

• See https://codeigniter4.github.io/CodeIgniter4/libraries/pagination.html#customizing-the-links.

2. CI4 uses the actual page number only. You can't use the starting index (offset) for the items which is the default in CI3. So if you use offset, you have to convert page to offset.

$offset = max(($page - 1), 0) * $per_page;

3. CI4 gets the base URL automatically from the current URL. You can't set it by config.

Views

Copy View files

1. Copy application/views/* to app/Views/*.

Helpers

Copy Helper files

1. Copy application/helper/* to app/Helpers/*.

URL Helper

redirect()

1. CI4 changed redirect() API.

• See https://codeigniter4.github.io/CodeIgniter4/general/common_functions.html#redirect.
• Replace redirect($uri) with return redirect()->to($uri), when you can return Response object.
• Replace it withthrow new \CodeIgniter\Router\Exceptions\RedirectException($uri), when you cannot return Response object.
• Or you could use redirect_() that ci3-to-4-upgrade-helper provides after $this->load->helper('url').

base_url()

1. Up to version 4.3.1, CI4 base_url() removed the trailing slash. But the bug was fixed in v4.3.2.

url_title()

1. CI4's url_title() does not support the second param's 'dash' and 'underscore'. Replace them with '-' or '_'.

Common Functions

show_error()

1. CI4 does not have show_error()

• show_error() that ci3-to-4-upgrade-helper provides does not support the third argument $heading.
• If you want to show error page like CI3, you have to create error templates like app/Views/errors/html/error_500.php where 500 is the status code.
• In error templates, you can use $message which has the Exception message.

Language files

1. Copy language folders (application/language/*) to app/Language/.

Writable Paths

1. CI4 has new writable directory and the constant WRITEPATH. Adjust the paths when you write files.