Multi-Language Setup in CodeIgniter

The multi-language setup feature, also known as internationalization, is essential for any modern web application aiming for a global audience. In this tutorial, we'll walk you through how to enable multi-language setup in CodeIgniter. This solution primarily covers non-editable text within your application but doesn't delve into multi-language content retrieved from a database.

1. Configure Default Language

Open the `application/config/config.php` file and specify your site's default language:

$config['language'] = 'english';

2. Create Multi-Language Files

Create separate language files and place them within the `application/language/` directory, each in its own sub-directory (e.g., `english`, `indonesian`, `chinese`, `arabic`). Your language file structure should look like this:

• application/language/english/welcome_lang.php
• ...
• application/language/indonesian/welcome_lang.php
• ...
• application/language/chinese/welcome_lang.php
• ...
• application/language/arabic/welcome_lang.php
• ...
• ...

Sample language files would appear as follows:

`english/welcome_lang.php`

<?php
$lang['welcome_message'] = 'Welcome to our website!';
$lang['about_us'] = 'About Us';
?>

`indonesian/welcome_lang.php`

<?php
$lang['welcome_message'] = 'Selamat datang di website kami!';
$lang['about_us'] = 'Tentang Kami';
?>

`chinese/welcome_lang.php`

<?php
$lang['welcome_message'] = '欢迎来到我们的网站！';
$lang['about_us'] = '关于我们';
?>

`arabic/welcome_lang.php`

<?php
$lang['welcome_message'] = 'مرحبا بكم في موقعنا!';
$lang['about_us'] = 'معلومات عنا';
?>

3. Load Language Files

Open `application/controllers/welcome.php` and add the following code within the controller’s `__construct()` function to enable the multi-language setup in CodeIgniter:

public function __construct() {
    parent::__construct();
    $this->load->helper('language');
    $this->lang->load('welcome');
}

Next, open `application/config/hooks.php` and define a hook to dynamically load languages:

$hook['post_controller_constructor'] = array(
    'class'    => 'LanguageLoader',
    'function' => 'initialize',
    'filename' => 'LanguageLoader.php',
    'filepath' => 'hooks'
);

Create the `LanguageLoader` class in `LanguageLoader.php` inside the `application/hooks/` directory:

<?php
class LanguageLoader {
    function initialize() {
        $ci =& get_instance();
        $ci->load->helper('language');
        $site_lang = $ci->session->userdata('site_lang');
        if ($site_lang) {
            $ci->lang->load('message', $ci->session->userdata('site_lang'));
        } else {
            $ci->lang->load('message', 'english');
        }
    }
}
?>

4. Switch Between Different Languages

To facilitate a multi-language setup in CodeIgniter, create a `Langswitch` class in `langswitch.php` within the `application/controllers/` directory:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Langswitch extends CI_Controller {

    public function __construct() {
        parent::__construct();
        $this->load->helper('url');
    }

    public function switchLanguage($language = "") {
        $language =  ($language != "") ? $language : "english";
        $this->session->set_userdata('site_lang', $language);
        redirect(base_url());
    }
}
?>

5. Core System Setup for Pages

For your pages to work seamlessly with the multi-language setup in CodeIgniter, you'll need to configure the core system. Create an `MY_Config` class in `MY_Config.php` inside the `application/core/` directory:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class MY_Config extends CI_Config {

    function site_url($uri = '') {
        if (is_array($uri)) {
            $uri = implode('/', $uri);
        }

        if ($uri == '') {
            return parent::site_url($uri);
        }

        $CI =& get_instance();
        if (!$CI->lang->has_language($uri)) {
            $uri = $CI->lang->localized($uri);
        }

        return parent::site_url($uri);
    }
}
?>

Then, to correctly load the language for your multi-language setup in CodeIgniter, create an `MY_Lang` class in `MY_Lang.php` inside the `application/core/` directory:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class MY_Lang extends CI_Lang {

    var $languages = array(
        'en' => 'english',
        'id' => 'indonesian',
        'cn' => 'chinese',
        'sa' => 'arabic'
    );

    var $special = array(""); // Add any special URIs that don't need language prefix
    var $default_uri = '';

    function __construct() {
        parent::__construct();

        global $CFG;
        global $URI;
        global $RTR;

        $segment = $URI->segment(1);

        if (isset($this->languages[$segment])) { // URI with language -> ok
            $language = $this->languages[$segment];
            $CFG->set_item('language', $language);
        } else if ($this->is_special($segment)) { // special URI -> no redirect
            return;
        } else {
            $CFG->set_item('language', $this->languages[$this->default_lang()]);
            header("Location: " . $CFG->site_url($this->localized($this->default_uri)), TRUE, 302);
            exit;
        }
    }

    function lang() {
        global $CFG;
        $language = $CFG->item('language');

        $lang = array_search($language, $this->languages);
        if ($lang) {
            return $lang;
        }

        return NULL; // this should not happen
    }

    function is_special($uri) {
        $exploded = explode('/', $uri);
        if (in_array($exploded[0], $this->special)) {
            return TRUE;
        }
        if (isset($this->languages[$uri])) {
            return TRUE;
        }
        return FALSE;
    }

    function switch_uri($lang) {
        $CI =& get_instance();

        $uri = $CI->uri->uri_string();
        if ($uri != "") {
            $exploded = explode('/', $uri);
            if ($exploded[0] == $this->lang()) {
                $exploded[0] = $lang;
            }
            $uri = implode('/', $exploded);
        }
        return $uri;
    }

    function has_language($uri) {
        $first_segment = NULL;

        $exploded = explode('/', $uri);
        if (isset($exploded[0])) {
            if ($exploded[0] != '') {
                $first_segment = $exploded[0];
            } else if (isset($exploded[1]) && $exploded[1] != '') {
                $first_segment = $exploded[1];
            }
        }

        if ($first_segment != NULL) {
            return isset($this->languages[$first_segment]);
        }

        return FALSE;
    }

    function default_lang() {
        foreach ($this->languages as $lang => $language) {
            return $lang;
        }
    }

    function localized($uri) {
        if ($this->has_language($uri)
            || $this->is_special($uri)
            || preg_match('/(.+)\.[a-zA-Z0-9]{2,4}$/', $uri)) {
            // Do nothing
        } else {
            $uri = $this->lang() . '/' . $uri;
        }

        return $uri;
    }
}
?>

6. Set Default Route Controller

To ensure your multi-language setup in CodeIgniter routes correctly, configure your `application/config/routes.php` file:

$route['^en$'] = $route['default_controller'];
$route['^id$'] = $route['default_controller'];
$route['^cn$'] = $route['default_controller'];
$route['^sa$'] = $route['default_controller'];

7. Define Links to Switch Multi-Language

Finally, to allow users to switch languages in your multi-language setup in CodeIgniter, you'll need to define links in your views, pointing to the `Langswitch` controller:

<a href="<?php echo site_url('langswitch/switchLanguage/english'); ?>">English</a>
<a href="<?php echo site_url('langswitch/switchLanguage/indonesian'); ?>">Indonesian</a>
<a href="<?php echo site_url('langswitch/switchLanguage/chinese'); ?>">Chinese</a>
<a href="<?php echo site_url('langswitch/switchLanguage/arabic'); ?>">Arabic</a>

8. Fetching Line of Text

To display localized text within your views (e.g., in `application/views/welcome.php`), use the `lang()` function:

<h1><?php echo $this->lang->line('welcome_message'); ?></h1>
<p><?php echo $this->lang->line('about_us'); ?></p>