Why does sbt report "not found: value PlayScala" with Build.scala while build.sbt works? - scala

Question

I am creating a multi-module sbt project, with following structure:
<root>
----build.sbt
----project
----Build.scala
----plugins.sbt
----common
----LoggingModule
LoggingModule is a Play Framework project, while common is a simple Scala project.
In plugins.sbt:
resolvers += "Typesafe repo" at "http://repo.typesafe.com/typesafe/releases/"
addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.3.3")
While I have this in build.sbt, all works fine and it recognises PlayScala:
name := "Multi-Build"
lazy val root = project.in(file(".")).aggregate(common, LoggingModule).dependsOn(common, LoggingModule)
lazy val common = project in file("common")
lazy val LoggingModule = (project in file("LoggingModule")).enablePlugins(PlayScala)
However as soon I put this in project/Build.scala instead of `build.sbt' as follows:
object RootBuild extends Build {
lazy val root = project.in(file("."))
.aggregate(common, LoggingModule)
.dependsOn(common, LoggingModule)
lazy val common = project in file("common")
lazy val LoggingModule = (project in file("LoggingModule")).enablePlugins(PlayScala)
...//other settings
}
it generates error as:
not found: value PlayScala
lazy val LoggingModule = (project in file("LoggingModule")).enablePlugins(PlayScala)
^
How to solve the issue?

Answer 1

It's just a missing import.
In .sbt files, some things are automatically imported by default: contents of objects extending Plugin, and (>= 0.13.5) autoImport fields in AutoPlugins. This is the case of PlayScala.
In a Build.scala file, normal Scala import rules apply. So you have to import things a bit more explicitly. In this case, you need to import play.PlayScala (or use .enabledPlugins(play.PlayScala) directly).