Basic Play framework routing and web sockets example - scala

Question

I'm trying to learn how to use web sockets in Play 2.1, and I'm having trouble getting the web socket URL to work with my app's routing configuration. I started with a new Play application and the Play framework documentation on websockets.
Here is my conf/routes:
# Home page
GET / controllers.Application.index
# Websocket test site
GET /wstest controllers.Application.wstest
Then I added the wstest function to my controller class:
object Application extends Controller {
def index = Action {
Ok(views.html.index("Websocket Test"))
}
def wstest = WebSocket.using[String] { request =>
// Log events to the console
val in = Iteratee.foreach[String](println).mapDone { _ =>
Logger.info("Disconnected")
}
// Send a single 'Hello!' message
val out = Enumerator("Hello!")
(in, out)
}
}
However, so far, I can only access the websocket with the URL ws://localhost:9000/wstest (using the sample code at websocket.org/echo.html). I was looking at the sample/scala/websocket-chat app that comes with the Play framework, and it uses the routing configuration file to reference the websocket, like this:
var WS = window['MozWebSocket'] ? MozWebSocket : WebSocket
var chatSocket = new WS("#routes.Application.chat(username).webSocketURL()")
I tried replacing my websocket URL with #routes.Application.wstest.webSocketURL() and #routes.Application.wstest. The first one doesn't compile. The second one compiles, but the client and server don't exchange any messages.
How can I use my Play routing configuration to access this websocket? What am I doing wrong here?
Edit
Here is a screenshot of my compilation error, "Cannot find any HTTP Request Header here":

Answer 1

Without the compiler error it's hard to guess what might be the problem.
Either you have to use parens because of the implicit request, i.e. #routes.Application.wstest().webSocketURL(), or you have no implicit request in scope which is needed for the webSocketURL call.

Answer 2

Marius is right that there was no implicit request in scope. Here's how to get it in scope:
Update the index function in the controller:
def index = Action { implicit request =>
Ok(views.html.index("Websocket Test"))
}
Add the request as a curried parameter to index.scala.html:
#(message: String)(implicit request: RequestHeader)
#main(message) {
<script>
var output;
function init() {
output = document.getElementById("output");
testWebSocket();
}
function testWebSocket() {
websocket = new WebSocket("#routes.Application.wstest.webSocketURL()");
.
.
.
And now the RequestHeader is in scope.