This plugins provides:

• Route class for generating and matching urls with language prefix.
• Middleware (dispatcher filter or CakePHP < 3.3) which sets I18n::locale() based on language prefix in URL and also provides redirection to appropriate URL with language prefix when accessing site root.
• Class for retrieving translation messages stored in database instead of po/mo files.
• Validation class for auto translating validation message.
• A widget to generate select box with list of timezone identifiers.

• CakePHP 3.0+

composer require admad/cakephp-i18n

Load the plugin in config/bootstrap.php:

// Load the plugin.
Plugin::load('ADmad/I18n');

The I18nRoutes helps generating routes of style /:lang/:controller/:action.

For e.g. you can add routes to your routes.php similar to the ones shown below:

Router::scope('/', function ($routes) {
    $routes->connect(
        '/:controller',
        ['action' => 'index'],
        ['routeClass' => 'ADmad/I18n.I18nRoute']
    );
    $routes->connect(
        '/:controller/:action/*',
        [],
        ['routeClass' => 'ADmad/I18n.I18nRoute']
    );
});

Fragment /:lang will be auto prefixed to the routes which allows matching URLs like /en/posts, /en/posts/add etc. The :lang element is persisted so that when generating URLs if you don't provide the lang key in URL array it will be automatically added based on current URL.

When connecting the routes you can use lang key in options to provide regular expression to match only languages which your app supports. Or your can set config value I18n.languages which the route class will use to auto generate regex for lang element matching:

Configure::write('I18n.languages', ['en', 'fr', 'de']);

Note: I18nRoute extends core's DashedRoute so the URL fragments will be inflected accordingly.

Create database table using sql file provided in config folder.

Add code similar to what's shown below in your app's config/bootstrap.php:

// Configure I18n to use DbMessagesLoader for default domain. You need to do
// this for each domain separately.
I18n::config('default', function ($domain, $locale) {
    return new \ADmad\I18n\I18n\DbMessagesLoader(
        $domain,
        $locale
    );
});

Use can use ADmad.I18n shell to extract the translation message from your code files and populate the translations table. Updating the db records with translations for each language is upto you. Having the messages in a table instead of files make it much to make a web interface for managing translations.

You can setup the I18nMiddleware in your src/Application::middleware() as shown:

$middlware->add(new \ADmad\I18n\Middlware\I18nMiddleware([
    'defaultLanguage' => 'en',
    'languages' => [
        'en' => ['locale' => 'en_US'],
        'fr' => ['locale' => 'fr_FR']
    ],
]));

The keys of languages array are the language prefixes you use in your URL.

In your AppView::initialize() configure the FormHelper to use TimezoneWidget.

// src/View/AppView.php
public function initialize()
{
    $this->loadHelper('Form', [
        'widget' => [
            'timezone' => ['ADmad/I18n.Timezone']
        ]
    ]);
}

You can generate a select box with timezone identifiers like:

// Generates select box with list of all timezone identifiers grouped by regions.
$this->Form->input('fieldname', ['type' => 'timezone']);

// Generates select box with list of timezone identifiers for specified regions.
$this->Form->input('fieldname', [
    'type' => 'timezone',
    'options' => [
        'Asia' => DateTimeZone::ASIA,
        'Europe' => DateTimeZone::EUROPE
    ]
]);

As shown in example above note that unlike normal select box, options is now an associative array of valid timezone regions where the key will be used as optgroup in the select box.