在Play 2.6.3项目的根文件夹中找不到非Play Sbt Scala子项目

Question

I used the Gitter Play Scala Seed template to create a starter project. I later decided to add another one of my projects as a sub-project to this one by following these and these instructions. However, even though I added the sub-project folder and referred to it from my build.sbt file, whenever I run update (or any of its dependencies) I am getting an error saying that the sub-project cannot be found.

Here's the build.sbt which I am using in the play project (my base project) folder:

name := """play-scala-starter-example"""

version := "1.0-SNAPSHOT"

lazy val root = (project in file("."))
    .enablePlugins(PlayScala)
    .aggregate(lettergenerator)
    .dependsOn(lettergenerator)

// I have also tried it explicitly:
// lazy val lettergenerator = (project in file("lettergenerator"))
lazy val lettergenerator = project

resolvers += Resolver.sonatypeRepo("snapshots")

scalaVersion := "2.12.2"

libraryDependencies += guice
libraryDependencies += "org.scalatestplus.play" %% "scalatestplus-play" % "3.0.0" % Test
libraryDependencies += "com.h2database" % "h2" % "1.4.194"

This is my folder structure:

play-scala-starter-example
 ├ app
 ├ build.sbt
 ├ conf
 ├ lettergenerator
 │  ├ build.sbt
 │  ├ LICENSE
 │  ├ project
 │  ├ README.md
 │  ├ src
 │  └ TODO.md
 ├ LICENSE
 ├ logs
 ├ project
 ├ public
 ├ README.md
 ├ target
 └ test

Here's the stack trace from the error:

[info] Loading global plugins from /home/claudiusbr/.sbt/0.13/plugins
[info] Loading project definition from /home/claudiusbr/test/play-scala-starter-example/project
java.lang.RuntimeException: No project 'lettergenerator' in 'file:/home/claudiusbr/test/play-scala-starter-example/'.
Valid project IDs: root
        at scala.sys.package$.error(package.scala:27)
        at sbt.Load$$anonfun$checkAll$2$$anonfun$apply$16.apply(Load.scala:401)
        at sbt.Load$$anonfun$checkAll$2$$anonfun$apply$16.apply(Load.scala:396)
        at scala.collection.immutable.List.foreach(List.scala:318)
        at sbt.Load$$anonfun$checkAll$2.apply(Load.scala:396)
        at sbt.Load$$anonfun$checkAll$2.apply(Load.scala:396)
        at scala.collection.TraversableLike$WithFilter$$anonfun$foreach$1.apply(TraversableLike.scala:772)
        at scala.collection.immutable.Map$Map1.foreach(Map.scala:109)
        at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:771)
        at sbt.Load$.checkAll(Load.scala:396)
        at sbt.Load$.loadURI(Load.scala:321)
        at sbt.Load$.load(Load.scala:316)
        at sbt.Load$.load(Load.scala:305)
        at sbt.Load$$anonfun$4.apply(Load.scala:146)
        at sbt.Load$$anonfun$4.apply(Load.scala:146)
        at sbt.Load$.timed(Load.scala:1025)
        at sbt.Load$.apply(Load.scala:146)
        at sbt.Load$.defaultLoad(Load.scala:39)
        at sbt.BuiltinCommands$.liftedTree1$1(Main.scala:548)
        at sbt.BuiltinCommands$.doLoadProject(Main.scala:548)
        at sbt.BuiltinCommands$$anonfun$loadProjectImpl$2.apply(Main.scala:540)
        at sbt.BuiltinCommands$$anonfun$loadProjectImpl$2.apply(Main.scala:540)
        at sbt.Command$$anonfun$applyEffect$1$$anonfun$apply$2.apply(Command.scala:59)
        at sbt.Command$$anonfun$applyEffect$1$$anonfun$apply$2.apply(Command.scala:59)
        at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:61)
        at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:61)
        at sbt.Command$.process(Command.scala:93)
        at sbt.MainLoop$$anonfun$1$$anonfun$apply$1.apply(MainLoop.scala:96)
        at sbt.MainLoop$$anonfun$1$$anonfun$apply$1.apply(MainLoop.scala:96)
        at sbt.State$$anon$1.doX$1(State.scala:183)
        at sbt.State$$anon$1.process(State.scala:190)
        at sbt.MainLoop$$anonfun$1.apply(MainLoop.scala:96)
        at sbt.MainLoop$$anonfun$1.apply(MainLoop.scala:96)
        at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
        at sbt.MainLoop$.next(MainLoop.scala:96)
        at sbt.MainLoop$.run(MainLoop.scala:89)
        at sbt.MainLoop$$anonfun$runWithNewLog$1.apply(MainLoop.scala:68)
        at sbt.MainLoop$$anonfun$runWithNewLog$1.apply(MainLoop.scala:63)
        at sbt.Using.apply(Using.scala:24)
        at sbt.MainLoop$.runWithNewLog(MainLoop.scala:63)
        at sbt.MainLoop$.runAndClearLast(MainLoop.scala:46)
        at sbt.MainLoop$.runLoggedLoop(MainLoop.scala:30)
        at sbt.MainLoop$.runLogged(MainLoop.scala:22)
        at sbt.StandardMain$.runManaged(Main.scala:109)
        at sbt.xMain.run(Main.scala:38)
        at xsbt.boot.Launch$$anonfun$run$1.apply(Launch.scala:109)
        at xsbt.boot.Launch$.withContextLoader(Launch.scala:128)
        at xsbt.boot.Launch$.run(Launch.scala:109)
        at xsbt.boot.Launch$$anonfun$apply$1.apply(Launch.scala:35)
        at xsbt.boot.Launch$.launch(Launch.scala:117)
        at xsbt.boot.Launch$.apply(Launch.scala:18)
        at xsbt.boot.Boot$.runImpl(Boot.scala:41)
        at xsbt.boot.Boot$.main(Boot.scala:17)
        at xsbt.boot.Boot.main(Boot.scala)
[error] No project 'lettergenerator' in 'file:/home/claudiusbr/test/play-scala-starter-example/'.
[error] Valid project IDs: root
[error] Use 'last' for the full log.
Project loading failed: (r)etry, (q)uit, (l)ast, or (i)gnore? q

I have tried looking at what seems to be a similar question for a different error , but nothing I can see there seems to help with my issue.

I am using sbt version 0.13.16 and Scala 2.12.3 for my lettergenerator , but I tried respectively both these and 0.13.15 / 2.12.2 for my play project's build.sbt and neither worked.

It's possible I am missing something obvious, but so far I am not sure what else I could do, so would appreciate any assistance.

Answer 1

I think you need to point lettergenerator to the right sub-directory of your project, ie, replace

lazy val lettergenerator = project

with

lazy val lettergenerator = project.in(file("lettergenerator"))

---

With multiple sub-projects I recommend to switch from the default play layout to the default SBT layout and move the play application into a separate sub-directory as well, ie, backend or server or whatever.

I also advise against having multiple build.sbt files for different sub-projects. In my experience this doesn't scale well and quickly becomes confusing as sub-projects become more complex.

Instead I recommend to keep a single top-level build.sbt and define all settings per-project in .settings . For common settings that affect the whole project, eg, version , I use .settings(inThisBuild(…)) on the root project ( simple example , or more complex real world example ).