Handling Etags with Play

Controller.scala

def taggedResult(request: RequestHeader, tag: String)(result: => Result): Result =
  request.headers.get(IF_NONE_MATCH) match {
    case Some(t) if t == tag => NotModified
    case _ => result.withHeaders(ETAG -> tag)
  }

// Example of use:
val javascriptRoutes = {
  val router =
    JavaScriptReverseRouter("routes", None, hostname,
      routes.javascript.Controller.search,
      routes.javascript.Controller.geocode
    )
  val routerTag = router.body.hashCode.toString

  Action { request =>
    taggedResult(request, routerTag) {
      Ok(JavaScript(s"""define(function () { ${router.body}; return routes })"""))
    }
  }
}