Reverse Routes

URL support and reverse routes

ScalatraBase provides two instances that provide you with relative URLs. The url method will return a string that can be used in your output or a redirect statement.

The scalatra-http-demo is a good place to start if you'd like to see working url-related examples.

In Scalatra 2.0.x, you used to need to extend the UrlSupport trait, but that’s now been moved into ScalatraBase, so all you need is:

class MyApp extends ScalatraServlet {


Page relative url:

  // This will redirect to http://<host>/page-relative

Context relative url:

  // This will redirect to http://<host>/<context>/context-relative

Mapped params:

get("/") {
  // This will redirect to http://<host>/<context>/en-to-es?one=uno&two=dos
  redirect( url("/en-to-es", Map("one" -> "uno", "two" -> "dos")) )

Reverse routes:

It is possible to save your routes as variables so that they have convenient handles:

class MyApp extends ScalatraServlet with UrlGeneratorSupport {
  // When you create a route, you can save it as a variable
  val viewUser = get("/user/:id") {
     // your user action would go here

  post("/user/new") {
    // url method provided by UrlGeneratorSupport.  Pass it the route
    // and the params.
    redirect(url(viewUser, "id" ->

There’s also a ScalateUrlGeneratorSupport. It reflectively finds all members of your app of type Route (e.g., viewUser above) and makes them available in your templates. You should then be able to do something like this right in your templates:

url(viewUser, "id" -> 1)