Laky Laky - 2 months ago 12
Scala Question

Routes with optional parameter - Play 2.1 Scala

So in Play 2.0 I had this:

GET /tasks/add controllers.Tasks.addTask(parentId: Option[Long] = None)
GET /tasks/:parentId/add controllers.Tasks.addTask(parentId: Option[Long])

With a controller method like this:

def addTask(parentId: Option[Long]) = Action {
Ok(views.html.addTask(taskForm, parentId))

And it was working. As I migrated to 2.1, it seems to complain about these lines with:
No URL path binder found for type Option[Long]. Try to implement an implicit PathBindable for this type.
Basically, what I am trying to accomplish is to have route
and route
link to the same method that accepts an
. Any idea how to do this? Thanks.

Ok, so I got a kind of it's not a bug, it's a feature response on Lighthouse: "We removed Option[Long] support in path bindables since it doesn't make sense to have a optional path parameter. You can implement your own path bindable that supports it if you please." So far I have 2 solutions, passing -1 as parentId, which I do not really like. Or having 2 different methods, which probably makes more sense in this case. Implementing the PathBindable doesn't seem too feasible right now, so I will probably stick with having 2 methods.


Play 2.0 supported Option in path parameters, Play 2.1 no longer supports this, they removed the PathBindable for Option.

One possible solution would be:

package extensions
import play.api.mvc._
object Binders {
  implicit def OptionBindable[T : PathBindable] = new PathBindable[Option[T]] {
    def bind(key: String, value: String): Either[String, Option[T]] =
        bind(key, value).
          left => Left(left),
          right => Right(Some(right))

    def unbind(key: String, value: Option[T]): String = value map (_.toString) getOrElse ""

And add this to Build.scala using routesImport += "extensions.Binders._". Run play clean ~run and it should work. Reloading the Binders on the fly only sometimes works.