Internationalization & Localization

One of the best ways for your applications to reach a larger audience is to cater for multiple languages. This can often prove to be a daunting task, but the internationalization and localization features in CakePHP make it much easier.

First, it’s important to understand some terminology. Internationalization refers to the ability of an application to be localized. The term localization refers to the adaptation of an application to meet specific language (or culture) requirements (i.e., a “locale”). Internationalization and localization are often abbreviated as i18n and l10n respectively; 18 and 10 are the number of characters between the first and last character.

Internationalizing Your Application

There are only a few steps to go from a single-language application to a multi-lingual application, the first of which is to make use of the `__() <https://api.cakephp.org/file/cake/basics.php#function-__>`_ function in your code. Below is an example of some code for a single-language application:

<h2>Posts</h2>

To internationalize your code, all you need to do is to wrap strings in the translate function like so:

<h2><?php __('Posts') ?></h2>

If you do nothing further, these two code examples are functionally identical - they will both send the same content to the browser. The `__() function <https://api.cakephp.org/file/cake/basics.php#function-__>`_ will translate the passed string if a translation is available, or return it unmodified. It works similar to other Gettext implementations (as do the other translate functions, such as `__d() <https://api.cakephp.org/file/cake/basics.php#function-__d>`_, `__n() <https://api.cakephp.org/file/cake/basics.php#function-__n>`_ etc)

With your code ready to be multilingual, the next step is to create your pot file, which is the template for all translatable strings in your application. To generate your pot file(s), all you need to do is run the i18n console task, which will look for where you’ve used a translate function in your code and generate your pot file(s) for you. You can and should re-run this console task any time you change the translations in your code.

The pot file(s) themselves are not used by CakePHP, they are the templates used to create or update your po files, which contain the translations. Cake will look for your po files in the following location:

/app/locale/<locale>/LC_MESSAGES/<domain>.po

The default domain is ‘default’, therefore your locale folder would look something like this:

/app/locale/eng/LC_MESSAGES/default.po (English)
/app/locale/fre/LC_MESSAGES/default.po (French)
/app/locale/por/LC_MESSAGES/default.po (Portuguese)

To create or edit your po files it’s recommended that you do not use your favorite editor. To create a po file for the first time it is possible to copy the pot file to the correct location and change the extension however unless you’re familiar with their format, it’s quite easy to create an invalid po file or to save it as the wrong charset (if you’re editing manually, use UTF-8 to avoid problems). There are free tools such as PoEdit which make editing and updating your po files an easy task; especially for updating an existing po file with a newly updated pot file.

The three-character locale codes conform to the ISO 639-2 standard, although if you create regional locales (en_US, en_GB, etc.) cake will use them if appropriate.

there is a 1014-character limit for each msgstr value (source needed).

Remember that po files are useful for short messages, if you find you want to translate long paragraphs, or even whole pages - you should consider implementing a different solution. e.g.:

// App Controller Code.
function beforeFilter() {
    $locale = Configure::read('Config.language');
    if ($locale && file_exists(VIEWS . $locale . DS . $this->viewPath)) {
        // e.g. use /app/views/fre/pages/tos.ctp instead of /app/views/pages/tos.ctp
        $this->viewPath = $locale . DS . $this->viewPath;
    }
}

or

// View code
echo $this->element(Configure::read('Config.language') . '/tos')

Localization in CakePHP

To change or set the language for your application, all you need to do is the following:

Configure::write('Config.language', 'fre');

This tells Cake which locale to use (if you use a regional locale, such as fr_FR, it will use the ISO 639-2 locale as a fallback if it doesn’t exist), you can change the language at any time, e.g. in your bootstrap if you’re setting the application default language, in your (app) controller beforeFilter if it’s specific to the request or user, or in fact anytime at all before you want a message in a different language.

It’s a good idea to serve up public content available in multiple languages from a unique url - this makes it easy for users (and search engines) to find what they’re looking for in the language they are expecting. There are several ways to do this, it can be by using language specific subdomains (en.example.com, fra.example.com, etc.), or using a prefix to the url such as is done with this application. You may also wish to glean the information from the browser’s user-agent, among other things.

As mentioned in the previous section, displaying localized content is done using the __() convenience function, or one of the other translation functions all of which are globally available, but probably be best utilized in your views. The first parameter of the function is used as the msgid defined in the .po files.

Remember to use the return parameter for the various __* methods if you don’t want the string echo’ed directly. For example:

<?php
echo $form->error(
    'Card.cardNumber',
    __("errorCardNumber", true),
    array('escape' => false)
);
?>

If you would like to have all of your validation error messages translated by default, a simple solution would be to add the following code in you app_model.php:

function invalidate($field, $value = true) {
    return parent::invalidate($field, __($value, true));
}

The i18n console task will not be able to determine the message id from the above example, which means you’ll need to add the entries to your pot file manually (or via your own script). To prevent the need to edit your default.po(t) file every time you run the i18n console task, you can use a different domain such as:

function invalidate($field, $value = true) {
    return parent::invalidate($field, __d('validation_errors', $value, true));
}

This will look for $value in the validation_errors.po file.

There’s one other aspect of localizing your application which is not covered by the use of the translate functions, and that is date/money formats. Don’t forget that CakePHP is PHP :), therefore to set the formats for these things you need to use `setlocale <http://www.php.net/setlocale>`_.

If you pass a locale that doesn’t exist on your computer to `setlocale <http://www.php.net/setlocale>`_ it will have no effect. You can find the list of available locales by running the command $locale -a in a terminal.