Note: This section is under development.
Internationalization (I18N) refers to the process of designing a software application so that it can be adapted to various languages and regions without engineering changes. For Web applications, this is of particular importance because the potential users may be worldwide.
There are two languages defined in Yii application: [[yii\base\Application::$sourceLanguage|source language]] and [[yii\base\Application::$language|target language]].
Source language is the language original application messages are written in such as:
echo \Yii::t('app', 'I am a message!');Tip: Default is English and it's not recommended to change it. The reason is that it's easier to find people translating from English to any language than from non-English to non-English.
Target language is what's currently used. It's defined in application configuration like the following:
// ...
return [
'id' => 'applicationID',
'basePath' => dirname(__DIR__),
'language' => 'ru-RU' // <- here!
// ...
]Later you can easily change it in runtime:
\Yii::$app->language = 'zh-CN';Format is ll-CC where ll is two- or three-letter lowercase code for a language according to
ISO-639 and CC is country code according to
ISO-3166.
If there's no translation for ru-RU Yii will try ru as well before failing.
Note: you can further customize details specifying language as documented in the ICU project.
Yii basic message translation in its basic variant works without additional PHP extension. What it does is finding a
translation of the message from source language into target language. Message itself is specified as the second
\Yii::t method parameter:
echo \Yii::t('app', 'This is a string to translate!');Yii tries to load appropriate translation from one of the message sources defined via i18n component configuration:
'components' => [
// ...
'i18n' => [
'translations' => [
'app*' => [
'class' => 'yii\i18n\PhpMessageSource',
//'basePath' => '@app/messages',
//'sourceLanguage' => 'en-US',
'fileMap' => [
'app' => 'app.php',
'app/error' => 'error.php',
],
],
],
],
],In the above app* is a pattern that specifies which categories are handled by the message source. In this case we're
handling everything that begins with app. You can also specify default translation, for more info see this example.
class defines which message source is used. The following message sources are available:
- PhpMessageSource that uses PHP files.
- GettextMessageSource that uses GNU Gettext MO or PO files.
- DbMessageSource that uses database.
basePath defines where to store messages for the currently used message source. In this case it's messages directory
in your application directory. In case of using database this option should be skipped.
sourceLanguage defines which language is used in \Yii::t second argument. If not specified, application's source
language is used.
fileMap specifies how message categories specified in the first argument of \Yii::t() are mapped to files when
PhpMessageSource is used. In the example we're defining two categories app and app/error.
Instead of configuring fileMap you can rely on convention which is BasePath/messages/LanguageID/CategoryName.php.
You can add parameters to a translation message that will be substituted with the corresponding value after translation. The format for this is to use curly brackets around the parameter name as you can see in the following example:
$username = 'Alexander';
echo \Yii::t('app', 'Hello, {username}!', [
'username' => $username,
]);Note that the parameter assignment is without the brackets.
$sum = 42;
echo \Yii::t('app', 'Balance: {0}', $sum);Tip: Try keep message strings meaningful and avoid using too many positional parameters. Remember that translator has source string only so it should be obvious about what will replace each placeholder.
In order to use advanced features you need to install and enable intl PHP
extension. After installing and enabling it you will be able to use extended syntax for placeholders. Either short form
{placeholderName, argumentType} that means default setting or full form {placeholderName, argumentType, argumentStyle}
that allows you to specify formatting style.
Full reference is available at ICU website but since it's a bit cryptic we have our own reference below.
$sum = 42;
echo \Yii::t('app', 'Balance: {0, number}', $sum);You can specify one of the built-in styles (integer, currency, percent):
$sum = 42;
echo \Yii::t('app', 'Balance: {0, number, currency}', $sum);Or specify custom pattern:
$sum = 42;
echo \Yii::t('app', 'Balance: {0, number, ,000,000000}', $sum);echo \Yii::t('app', 'Today is {0, date}', time());Built in formats (short, medium, long, full):
echo \Yii::t('app', 'Today is {0, date, short}', time());Custom pattern:
echo \Yii::t('app', 'Today is {0, date, YYYY-MM-dd}', time());echo \Yii::t('app', 'It is {0, time}', time());Built in formats (short, medium, long, full):
echo \Yii::t('app', 'It is {0, time, short}', time());Custom pattern:
echo \Yii::t('app', 'It is {0, date, HH:mm}', time());echo \Yii::t('app', '{n,number} is spelled as {n, spellout}', ['n' => 42]);echo \Yii::t('app', 'You are {n, ordinal} visitor here!', ['n' => 42]);Will produce "You are 42nd visitor here!".
echo \Yii::t('app', 'You are here for {n, duration} already!', ['n' => 47]);Will produce "You are here for 47 sec. already!".
Different languages have different ways to inflect plurals. Some rules are very complex so it's very handy that this functionality is provided without the need to specify inflection rule. Instead it only requires your input of inflected word in certain situations.
echo \Yii::t('app', 'There {n, plural, =0{are no cats} =1{is one cat} other{are # cats}}!', ['n' => 0]);Will give us "There are no cats!".
In the plural rule arguments above =0 means exactly zero, =1 stands for exactly one other is for any other number.
# is replaced with the n argument value. It's not that simple for languages other than English. Here's an example
for Russian:
Здесь {n, plural, =0{котов нет} =1{есть один кот} one{# кот} few{# кота} many{# котов} other{# кота}}!
In the above it worth mentioning that =1 matches exactly n = 1 while one matches 21 or 101.
Note that if you are using placeholder twice and one time it's used as plural another one should be used as number else you'll get "Inconsistent types declared for an argument: U_ARGUMENT_TYPE_MISMATCH" error:
Total {count, number} {count, plural, one{item} other{items}}.
To learn which inflection forms you should specify for your language you can referrer to rules reference at unicode.org.
You can select phrases based on keywords. The pattern in this case specifies how to map keywords to phrases and provides a default phrase.
echo \Yii::t('app', '{name} is {gender} and {gender, select, female{she} male{he} other{it}} loves Yii!', [
'name' => 'Snoopy',
'gender' => 'dog',
]);Will produce "Snoopy is dog and it loves Yii!".
In the expression female and male are possible values. other handler values that do not match. Strings inside
brackets are sub-expressions so could be just a string or a string with more placeholders.
You can specify default translation that will be used as a fallback for categories that don't match any other translation.
This translation should be marked with *. In order to do it add the following to the config file (for the yii2-basic application it will be web.php):
//configure i18n component
'i18n' => [
'translations' => [
'*' => [
'class' => 'yii\i18n\PhpMessageSource'
],
],
],Now you can use categories without configuring each one that is similar to Yii 1.1 behavior.
Messages for the category will be loaded from a file under default translation basePath that is @app/messages:
echo Yii::t('not_specified_category', 'message from unspecified category');Message will be loaded from @app/messages/<LanguageCode>/not_specified_category.php.
If you want to translate messages for a module and avoid using a single translation file for all messages, you can make it like the following:
<?php
namespace app\modules\users;
use Yii;
class Module extends \yii\base\Module
{
public $controllerNamespace = 'app\modules\users\controllers';
public function init()
{
parent::init();
$this->registerTranslations();
}
public function registerTranslations()
{
Yii::$app->i18n->translations['modules/users/*'] = [
'class' => 'yii\i18n\PhpMessageSource',
'sourceLanguage' => 'en-US',
'basePath' => '@app/modules/users/messages',
'fileMap' => [
'modules/users/validation' => 'validation.php',
'modules/users/form' => 'form.php',
...
],
];
}
public static function t($category, $message, $params = [], $language = null)
{
return Yii::t('modules/users/' . $category, $message, $params, $language);
}
}In the example above we are using wildcard for matching and then filtering each category per needed file. Instead of using fileMap you can simply
use convention of category mapping to the same named file and use Module::t('validation', 'your custom validation message') or Module::t('form', 'some form label') directly.
Same rules can be applied for widgets too, for example:
<?php
namespace app\widgets\menu;
use yii\base\Widget;
use Yii;
class Menu extends Widget
{
public function init()
{
parent::init();
$this->registerTranslations();
}
public function registerTranslations()
{
$i18n = Yii::$app->i18n;
$i18n->translations['widgets/menu/*'] = [
'class' => 'yii\i18n\PhpMessageSource',
'sourceLanguage' => 'en-US',
'basePath' => '@app/widgets/menu/messages',
'fileMap' => [
'widgets/menu/messages' => 'messages.php',
],
];
}
public function run()
{
echo $this->render('index');
}
public static function t($category, $message, $params = [], $language = null)
{
return Yii::t('widgets/menu/' . $category, $message, $params, $language);
}
}Instead of using fileMap you can simply use convention of category mapping to the same named file and use Menu::t('messages', 'new messages {messages}', ['{messages}' => 10]) directly.
Note: For widgets you also can use i18n views, same rules as for controllers are applied to them too.
Sometimes you want to correct default framework message translation for your application. In order to do so configure
i18n component like the following:
'components' => [
'i18n' => [
'translations' => [
'yii' => [
'class' => 'yii\i18n\PhpMessageSource',
'sourceLanguage' => 'en-US',
'basePath' => '/path/to/my/message/files'
],
],
],
],Now you can place your adjusted translations to /path/to/my/message/files.
If the translation is missing at the source, Yii displays the requested message content. Such behavior very convenient in case your raw message is a valid verbose text. However, sometimes it is not enough. You may need to perform some custom processing of the situation, when requested translation is missing at the source. This can be achieved via 'missingTranslation' event of the [[yii\i18n\MessageSource]].
For example: lets mark all missing translations with something notable, so they can be easily found at the page. First we need to setup event handler, this can be done via configuration:
'components' => [
// ...
'i18n' => [
'translations' => [
'app*' => [
'class' => 'yii\i18n\PhpMessageSource',
'fileMap' => [
'app' => 'app.php',
'app/error' => 'error.php',
],
'on missingTranslation' => ['TranslationEventHandler', 'handleMissingTranslation']
],
],
],
],Now we need to implement own handler:
use yii\i18n\MissingTranslationEvent;
class TranslationEventHandler
{
public static function(MissingTranslationEvent $event) {
$event->translatedMessage = "@MISSING: {$event->category}.{$event->message} FOR LANGUAGE {$event->language} @";
}
}If [[yii\i18n\MissingTranslationEvent::translatedMessage]] is set by event handler it will be displayed as translation result.
Attention: each message source handles its missing translations separately. If you are using several message sources and wish them treat missing translation in the same way, you should assign corresponding event handler to each of them.
You can use i18n in your views to provide support for different languages. For example, if you have view views/site/index.php and
you want to create special case for russian language, you create ru-RU folder under the view path of current controller/widget and
put there file for russian language as follows views/site/ru-RU/index.php.
Note: If language is specified as
en-USand there are no corresponding views, Yii will try views underenbefore using original ones.
See the data formatter section for details.