Support Scala 3, drop Scala 2.12 & Play 2.8

[rtyley]

Need to import play.api.libs.ws._ for the BodyWritable[Map[String, Seq[String]]]

Panda's OAuth class posts some url-encoded data (defined as Map[String, Seq[String]] in Scala) with ws.url(dd.token_endpoint).post, and this needs an implicit instance of BodyWritable[Map[String, Seq[String]]] in order to work! For some reason, in Scala 2, the compiler was able to find the correct implicit somewhere, but in Scala 3 we get a compilation error:

[error] 81 |        }.flatMap { response =>
[error]    |         ^
[error]    |Cannot find an instance of Map[K, Seq[String]] to WSBody. Define a BodyWritable[Map[K, Seq[String]]] or extend play.api.libs.ws.ahc.DefaultBodyWritables
[error]    |
[error]    |where:    K is a type variable with constraint >: String
[error]    |
[error]    |One of the following imports might fix the problem:
[error]    |
[error]    |
[error]    |One of the following imports might fix the problem:
[error]    |
[error]    |  import play.api.libs.ws.DefaultBodyWritables.writeableOf_urlEncodedForm
[error]    |  import play.api.libs.ws.WSBodyWritables.writeableOf_urlEncodedForm
[error]    |  import play.api.libs.ws.writeableOf_urlEncodedForm

Importing the whole ws package fixes the problem:

import play.api.libs.ws._

[rtyley]

Explicitly declaring the return type is necessary here or Scala 3 reports an 'ambiguous overload' error:

[error] -- [E051] Reference Error: /Users/Roberto_Tyley/code/pan-domain-authentication/pan-domain-auth-example/app/controllers/AdminController.scala:42:15 
[error] 42 |  def logout = Action { implicit request =>
[error]    |               ^^^^^^
[error]    |Ambiguous overload. The overloaded alternatives of method apply in trait ActionBuilder with types
[error]    | (block: play.api.mvc.Request[play.api.mvc.AnyContent] => play.api.mvc.Result):
[error]    |  play.api.mvc.Action[play.api.mvc.AnyContent]
[error]    | [A]
[error]    |  (bodyParser: play.api.mvc.BodyParser[A]):
[error]    |    play.api.mvc.ActionBuilder[play.api.mvc.Request, A]
[error]    |both match arguments (<?> => <?>)
[error]    |
[error]    | longer explanation available when compiling with `-explain`

[rtyley]

Panda's OAuth class posts some url-encoded data (defined as Map[String, Seq[String]] in Scala) with ws.url(dd.token_endpoint).post:

pan-domain-authentication/pan-domain-auth-play/src/main/scala/com/gu/pandomainauth/service/OAuth.scala

Lines 73 to 81 in 2c378ad

	ws.url(dd.token_endpoint).post {
	Map(
	"code" -> code,
	"client_id" -> Seq(config.clientId),
	"client_secret" -> Seq(config.clientSecret),
	"redirect_uri" -> Seq(redirectUrl),
	"grant_type" -> Seq("authorization_code")
	)
	}.flatMap { response =>

This needs an implicit instance of BodyWritable[Map[String, Seq[String]]] in order to work! For some reason, in Scala 2, the compiler was able to find the correct implicit somewhere, but in Scala 3 we get a compilation error:

[error] 81 |        }.flatMap { response =>
[error]    |         ^
[error]    |Cannot find an instance of Map[K, Seq[String]] to WSBody. Define a BodyWritable[Map[K, Seq[String]]] or extend play.api.libs.ws.ahc.DefaultBodyWritables
[error]    |
[error]    |where:    K is a type variable with constraint >: String
[error]    |
[error]    |One of the following imports might fix the problem:
[error]    |
[error]    |
[error]    |One of the following imports might fix the problem:
[error]    |
[error]    |  import play.api.libs.ws.DefaultBodyWritables.writeableOf_urlEncodedForm
[error]    |  import play.api.libs.ws.WSBodyWritables.writeableOf_urlEncodedForm
[error]    |  import play.api.libs.ws.writeableOf_urlEncodedForm

Importing the whole ws package fixes the problem.

[rtyley]

See:

• Upgrading to Play 3.0 maintaining-scala-projects#4

Note that the Play sbt-plugin is only required for the exampleApp app, not any of the other subprojects.

[gu-scala-library-release]

@rtyley has published a preview version of this PR with release workflow run #22, based on commit d7c7a35:

7.0.1-PREVIEW.support-scala-3-drop-scala-212-and-play-28.2024-12-10T1132.d7c7a35e

Want to make another preview release?

Click 'Run workflow' in the GitHub UI, specifying the support-scala-3-drop-scala-2.12-and-play-2.8 branch, or use the GitHub CLI command:

gh workflow run release.yml --ref support-scala-3-drop-scala-2.12-and-play-2.8

Want to make a full release after this PR is merged?

Click 'Run workflow' in the GitHub UI, leaving the branch as the default, or use the GitHub CLI command:

gh workflow run release.yml