How to use imports and implicits in Play Framework's routes file?

Question

What's the scope for routes file to find implicits like PathBindable or QueryStringBindable?

For custom types, it's trivial to simply define them in companion object like the following:

case class Foo(data: String)
object Foo {
  implicit val pathBinder: PathBindable[Foo] = ???
}

However, for existing types, it's unclear where to declare implicit to be found by routes file since we cannot do any custom import here.

So, What's the scope of implicits for routes file?

score 13 · Accepted Answer · answered Dec 31 '15 at 08:39

13

This doesn't directly answer the question, but it seems relevant...

You can include custom imports in the routes file by adding to the routesImport key in your build.sbt

For example:

import play.PlayImport.PlayKeys._

routesImport += "my.custom.package.Foo._"

That snippet is borrowed from a blog post I wrote a while ago entitled Using Play-Framework's PathBindable

answered Dec 31 '15 at 08:39

colinjwebb

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I knew there would be something like this! Thank you and happy new year :] – Daniel Shin Dec 31 '15 at 09:33
2

for me to get the `routesImport` key i had to import `play.sbt.routes.RoutesKeys.routesImport` – Peter Perháč Sep 25 '17 at 11:01
The blog post that the author mentioned has been moved to here: https://cjwebb.com/play-framework-path-binders/ – Matt Spataro Aug 15 '22 at 21:52

score 8 · Answer 2 · answered Jan 13 '17 at 14:17

we had a queryStringBindable that we needed to use and had a similar situation, we found this question which gave us a clue but the answer from colinjwebb is out of date.

Here's our example which goes from a string to an Option[LoginContext].

package controllers

import play.api.mvc.{Action, AnyContent, QueryStringBindable, Request}
...

object BindableLoginContext {

  implicit def queryStringBindable(implicit stringBinder: QueryStringBindable[String]) = new QueryStringBindable[LoginContext] {
    override def bind(key: String, params: Map[String, Seq[String]]): Option[Either[String, LoginContext]] =
      for {
        loginContextString <- stringBinder.bind(key, params)
      } yield {
        loginContextString match {
          case Right(value) if value.toLowerCase == "web" => Right(LoginContexts.Web)
          case Right(value) if value.toLowerCase == "api" => Right(LoginContexts.Api)
          case _ => Left(s"Unable to bind a loginContext from $key")
        }
      }

    override def unbind(key: String, loginContext: LoginContext): String = stringBinder.unbind(key, loginContext.toString)
  }
}

To use it we needed to use the following import:

import play.sbt.routes.RoutesKeys

and then add the object to the Project like this

lazy val microservice = Project(appName, file("."))
  .settings(
    RoutesKeys.routesImport += "controllers.BindableLoginContext._"
  )

How to use imports and implicits in Play Framework's routes file?

2 Answers2