Play JsMessages library
This library allows you to compute localized messages on client-side, in Play projects.
Basically, play-jsmessages takes the i18n messages of your Play application, sends them to the client-side as a JSON object and defines a JavaScript function returning a message value from a given language and the message key and arguments.
Take a look at the Scala and Java samples to see it in action.
Installation (using sbt)
Add a dependency on the following artifact:
libraryDependencies += "org.julienrf" %% "play-jsmessages" % "5.0.0"
The current 5.0.0 version is compatible with Play 2.8 and Scala 2.12 and 2.13.
Previous versions are available here:
4.0.0
for play-2.7 ;3.0.0
for play-2.6 ;2.1.0
for play-2.5 ;2.0.0
for play-2.4 ;1.6.2
for play-2.3 ;1.6.1
for play-2.2 ;1.5.2
for play-2.2 ;1.5.0
for play-2.1 ;1.3
for play-2.0 ;1.2.1
for play-2.0.
API Documentation
You can browse the online scaladoc.
Quick start
Select which messages you want to support on client-side
JsMessagesFactory
Get a The JsMessagesFactory
class is the starting point: it allows you to select which messages of your application
you want to support on client-side. You can use all the messages of the application or just a subset of them.
The simplest way to get a JsMessagesFactory
is via dependency injection:
import jsmessages.JsMessagesFactory
import javax.inject.Inject
class Application @Inject() (jsMessagesFactory: JsMessagesFactory) extends Controller {
}
The equivalent Java code is the following:
import jsmessages.JsMessagesFactory;
import javax.inject.Inject;
public class Application extends Controller {
@Inject
public Application(JsMessagesFactory jsMessagesFactory) {
}
}
The constructor of the JsMessagesFactory
itself needs to be injected a play.api.i18n.MessagesApi
parameter. By default,
Play defines a binding that uses a play.api.i18n.DefaultMessagesApi
, but you can disable this binding if you want to use something else.
For more control, you can also manually instantiate your JsMessagesFactory
:
val jsMessagesFactory = new JsMessagesFactory(someMessagesApi)
The equivalent Java code is the following:
JsMessagesFactory jsMessagesFactory = new JsMessagesFactory(someMessagesApi);
Note that, in Scala, you may want to use the JsMessagesFactoryComponents
trait that provides a jsMessagesFactory: JsMessagesFactory
member using an abstract messagesApi: MessagesApi
member.
Select which messages to use
You can either use all your i18n messages:
val jsMessages = jsMessagesFactory.all
Or, just an extensive subset:
val jsMessages = jsMessagesFactory.subset("error.required", "error.number")
Or, finally, an intensive subset:
val jsMessages = jsMessagesFactory.filtering(_.startsWith("error."))
The equivalent Java code of the above expressions are the following:
import jsmessages.JsMessages;
import play.libs.Scala;
JsMessages jsMessages = jsMessagesFactory.all();
JsMessages jsMessages = jsMessagesFactory.subset(Scala.varargs("error.required", "error.number"));
JsMessages jsMessages = jsMessagesFactory.filtering(new scala.runtime.AbstractFunction1<String, Boolean>() {
@Override
public Boolean apply(String key) {
return key.startsWith("error.");
}
});
Generate a JavaScript asset …
… for the client’s preferred language
Then, you typically want to define an action returning a JavaScript resource containing all the machinery to compute localized messages from client-side, using the client’s preferred lang:
val messages = Action { implicit request =>
Ok(jsMessages(Some("window.Messages")))
}
Note that for this to work the apply
method of jsMessages
needs to have an implicit play.api.i18n.Messages
value. You can
get one by mixing the play.api.i18n.I18nSupport
trait in your controller.
Or in Java:
@Inject
private MessagesApi messagesApi;
public Result messages(Http.Request request) {
return ok(jsMessages.apply(Scala.Option("window.Messages"), this.messagesApi.preferred(request)));
}
The above code creates a Play action that returns a JavaScript program containing the localized messages of the
application for the client language and defining a global function window.Messages
. This function returns a localized
message given its key and its arguments:
console.log(Messages('greeting', 'Julien')); // will print e.g. "Hello, Julien!" or "Bonjour Julien!"
The JavaScript function can also be supplied alternative keys that will be used if the main key is not defined. Keys will be tried in order until a defined key is found:
alert(Messages(['greeting', 'saluting'], 'Julien'));
The JavaScript function stores the messages map in a messages
property that is publicly accessible so you can update the messages without reloading the page:
// Update a single message
Messages.messages['greeting'] = 'Hi there {0}!';
// Update all messages
Messages.messages = {
'greeting': 'Hello, {0}!'
}
… for all the languages
Alternatively, you can use the all
method to generate a JavaScript program containing all the messages of the application
instead of just those of the client’s current language, making it possible to switch the language from client-side
without reloading the page:
val messages = Action {
Ok(jsMessages.all(Some("window.Messages")))
}
The equivalent Java code is the following:
public Result messages() {
return ok(jsMessages.all(Scala.Option("window.Messages")));
}
In this case, the generated JavaScript function takes an additional parameter corresponding to the language to use:
console.log(Messages('en', 'greeting', 'Julien')); // "Hello, Julien!"
console.log(Messages('fr', 'greeting', 'Julien')); // "Bonjour Julien!"
Moreover, the messages
property of the JavaScript function is a map of languages indexing maps of messages.
The JavaScript function can also be partially applied to fix its first parameter:
val messagesFr = Messages('fr'); // Use only the 'fr' messages
console.log(messagesFr('greeting', 'Julien')); // "Bonjour Julien!"
Note: if you pass undefined
as the language parameter, it will use the default messages.
Changelog
-
5.0.0
- Play 2.8.x compatibility.
-
4.0.0
- Play 2.7.x compatibility, cross-compiled for Scala 2.13.
-
3.0.0
- Play 2.6.x compatibility. All tests moved to scalatest+play and dependency injection.
-
2.0.0
- Play 2.4.x compatibility.
-
1.6.2
- Play 2.3.x compatibility.
-
1.6.1
- Fix crash when
undefined
is passed as the language parameter (thanks to Paul Dijou).
- Fix crash when
-
1.6.0
- Big changes in the API ;
- Make it possible to return messages of all languages (thanks to Paul Dijou) ;
- Discard methods returning HTML, keep just JavaScript.
-
1.5.2
- Export the
messages
property on client-side (thanks to Paul Dijou).
- Export the
-
1.5.1
- Play 2.2.x compatibility.
-
1.5.0
- Fix the
subset
method of the Java API (thanks to Seppel Hardt) ; - Refactor the whole API in order to make it more extensible (thanks to Jacques Bachellerie).
- Fix the
License
This content is released under the MIT License.