§Externalising messages and internationalization

§Specifying languages supported by your application

To specify your application’s languages, you need a valid language code, specified by a valid ISO Language Code, optionally followed by a valid ISO Country Code. For example, fr or en-US.

To start, you need to specify the languages that your application supports in its conf/application.conf file:

application.langs="en,en-US,fr"

§Changing language

To permanently change the user language, use the changeLang() method:

Controller.changeLang("cs");

The new value will be saved to the user’s language cookie.

§Externalizing messages

You can externalize messages in the conf/messages.xxx files.

The default conf/messages file matches all languages. You can specify additional language messages files, such as conf/messages.fr or conf/messages.en-US.

You can retrieve messages for the current language using the play.i18n.Messages object:

String title = Messages.get("home.title")

You can also specify the language explicitly:

String title = Messages.get(new Lang(Lang.forCode("fr")), "home.title")

Note: If you have a Request in the scope, it will provide a default Lang value corresponding to the preferred language extracted from the Accept-Language header and matching one of the application’s supported languages. You should also add a Lang implicit parameter to your template like this: @()(implicit lang: Lang).

§Use in templates

@import play.i18n._
@Messages.get("key")

§Formatting messages

Messages are formatted using the java.text.MessageFormat library. For example, if you have defined a message like this:

files.summary=The disk {1} contains {0} file(s).

You can then specify parameters as:

Messages.get("files.summary", d.files.length, d.name)

§Notes on apostrophes

Since Messages uses java.text.MessageFormat, please be aware that single quotes are used as a meta-character for escaping parameter substitutions.

For example, if you have the following messages defined:

info.error=You aren''t logged in!

example.formatting=When using MessageFormat, '''{0}''' is replaced with the first parameter.

you should expect the following results:

String errorMessage = Messages.get("info.error");
Boolean areEqual = errorMessage.equals("You aren't logged in!");

String errorMessage = Messages.get("example.formatting");
Boolean areEqual = errorMessage.equals("When using MessageFormat, '{0}' is replaced with the first parameter.");

§Retrieving supported languages from an HTTP request

You can retrieve a specific HTTP request’s supported languages:

public static Result index() {
  return ok(request().acceptLanguages());
}

Next: The application Global object