How can I use the Play Framework in a multi-project?

Question

I am struggling to find any information on how to use the Play Framework in a multi-project where the root project is a plain SBT one. Basically this is my project's layout:

/
- common
- some-other-projects
- my-play-project
- - app
- - - controllers
- - conf
- - - routes
- build.sbt

I can start the application by running my-play-project/run in the SBT console, but when I try to visit any page, I get a 500 and this error is logged:

[error] /someorg/backend/cms/conf/routes: package router does not exist
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   class ReversePostController
[error]   location: package controllers
[error] /someorg/backend/cms/conf/routes: package controllers.javascript does not exist
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   class ReversePostController
[error]   location: package controllers
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   variable RoutesPrefix
[error]   location: class controllers.routes
[error] /someorg/backend/cms/conf/routes: package controllers.javascript does not exist
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   variable RoutesPrefix
[error]   location: class controllers.routes.javascript
[error] (cms/compile:compileIncremental) javac returned nonzero exit code
[info] Compiling 6 Scala sources and 1 Java source to /someorg/backend/cms/target/classes...
[error] /someorg/backend/cms/conf/routes: package router does not exist
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   class ReversePostController
[error]   location: package controllers
[error] /someorg/backend/cms/conf/routes: package controllers.javascript does not exist
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   class ReversePostController
[error]   location: package controllers
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   variable RoutesPrefix
[error]   location: class controllers.routes
[error] /someorg/backend/cms/conf/routes: package controllers.javascript does not exist
[error] /someorg/backend/cms/conf/routes: cannot find symbol
[error]   symbol:   variable RoutesPrefix
[error]   location: class controllers.routes.javascript
[error] (cms/compile:compileIncremental) javac returned nonzero exit code
[error] application -

! @6pi9jna82 - Internal server error, for (GET) [/posts] ->

play.sbt.PlayExceptions$CompilationException: Compilation error[package router does not exist]
    at play.sbt.PlayExceptions$CompilationException$.apply(PlayExceptions.scala:27)
    at play.sbt.PlayExceptions$CompilationException$.apply(PlayExceptions.scala:27)
    at scala.Option.map(Option.scala:145)
    at play.sbt.run.PlayReload$$anonfun$taskFailureHandler$1.apply(PlayReload.scala:49)
    at play.sbt.run.PlayReload$$anonfun$taskFailureHandler$1.apply(PlayReload.scala:44)
    at scala.Option.map(Option.scala:145)
    at play.sbt.run.PlayReload$.taskFailureHandler(PlayReload.scala:44)
    at play.sbt.run.PlayReload$.compileFailure(PlayReload.scala:40)
    at play.sbt.run.PlayReload$$anonfun$compile$1.apply(PlayReload.scala:17)
    at play.sbt.run.PlayReload$$anonfun$compile$1.apply(PlayReload.scala:17)

Is there anything obvious I am missing that breaks this project? The controller is defined in the simplest possible way as explained in the documentation. The same goes for the only route I provide:

# Route
GET       /posts        controllers.PostController.list

// Controller
package controllers

import play.api.mvc.{Action, Controller}

class PostController extends Controller {
  def list = TODO
}

I'm using Play Framework 2.5.1 and the project build is defined as follows:

lazy val resolvers = ...

lazy val projectSettings = Seq(
  organization := "some-organization",
  scalaBinaryVersion := "2.11",
  scalaVersion := "2.11.7",
  externalResolvers := resolvers,
  moduleConfigurations := Seq(),
  retrieveManaged := true,
  concurrentRestrictions in Global += Tags.limit(Tags.Test, 1),
  transitiveClassifiers in Scope.GlobalScope := Seq("sources"),
  ivyLoggingLevel := UpdateLogging.Quiet,
  credentials += Credentials(Path.userHome / ".ivy2" / ".credentials"),
  crossPaths := false,
  publishMavenStyle := true,
  publishArtifact in (Compile, packageDoc) := false,
  publishArtifact in (Test, packageDoc) := false,
  javacOptions := Seq("-source", "1.8", "-target", "1.8", "-encoding", "utf8"),
  javaOptions := Seq("-server", "-XX:ReservedCodeCacheSize=192m", "-Xss2m"),
  javaOptions in Test := Seq("-server", "-Xmx2g", "-XX:ReservedCodeCacheSize=192m", "-Xss2m"),
  testFrameworks := Seq(TestFrameworks.ScalaTest, TestFrameworks.Specs2),
  noTestCompletion(),
  scalacOptions := Seq(
    "-deprecation",
    "-optimize",
    "-unchecked",
    "-encoding", "utf8",
    "-target:jvm-1.8",
    "-Xlog-reflective-calls",
    "-feature",
    "-language:_"
  ) ++ Seq(
      "by-name-right-associative",
      "delayedinit-select",
      "doc-detached",
      "inaccessible",
      "missing-interpolator",
      "nullary-override",
      "option-implicit",
      "package-object-classes",
      "poly-implicit-overload",
      "private-shadow",
      "unsound-match"
    ).map(x => s"-Xlint:$x"),
  compileOrder := CompileOrder.JavaThenScala,
  fork in Test := true,
  testOptions in Test := Seq(Tests.Filter(testName => testName.endsWith("Test") || testName.endsWith("Spec"))),
  testOptions in Test += Tests.Argument("-oDF"),
  testOptions in Test <+= (target in Test).map { t =>
    val testDir = t / "test-reports"
    val maybeJUnitXml = if (flag("sbt.test.nojunitxml")) Seq.empty else Seq("-u", testDir.getAbsolutePath)
    Tests.Argument(TestFrameworks.ScalaTest, maybeJUnitXml: _*)
  }
)

lazy val cms = (project in file("cms"))
  .settings(projectSettings)
  .dependsOn(common, commonTest % "test", model % compileTest)
  .enablePlugins(PlayScala)

lazy val root = (project in file("."))
  .settings(projectSettings)
  .aggregate(common, some-other-projects, cms) // TODO: Remove web

Answer 1

Update:

Now that you've posted your build.sbt file, I think the problem is the compile order. javac fails because it cannot find the mentioned package.

Try to use the default Mixed compilation order.

---

I suspect that you didn't enable the sbt-play plugin in the my-play-project subproject and hence your routes file wasn't compiled to my-play-project/target/scala-2.11/routes/main/router

In my-play-project/build.sbt, add:

enablePlugins(PlayScala)

Answer 2

Try adding the Play plugin declaration to the root project at /project/plugins.sbt