How to add dependency to Play framework project in Eclipse from second project?

Question

I am completely new to Java/Scala/Play/Eclipse. My experience so far is mostly with C# and Visual Studio.

I am wondering how to go about adding a dependency from a Scala project, in Eclipse, to my Play project, also in Eclipse. In Visual Studio, this was a matter of creating a class library project, and adding it as a reference to another project. The IDE managed the build process.

I've tried adding a new Project in my Build.scala file:

import sbt._
import Keys._
import play.Project._

object ApplicationBuild extends Build {

  val appName         = "blogUI"
  val appVersion      = "1.0-SNAPSHOT"

  val appDependencies = Seq(
    // Add your project dependencies here,
    jdbc,
    anorm
  )

  //  The new project; everything else was boilerplate
  val blogPlatform = Project("blogPlatform", file("blogPlatform")).settings(
    scalaVersion := "2.10.2"
  )

  val main = play.Project(appName, appVersion, appDependencies).settings(
    // Add your own project settings here      
  )

}

This doesn't work - it ends up creating an empty blogPlatform directory inside my blogUI Play project, instead of referring to my existing blogPlatform project. I'm also not familiar with sbt, so I could be totally misusing the tool.

I also tried adding the blogPlatform project as a dependency through Eclipse, which works - until I run "play eclipse" from a terminal. This wipes out any changes I had made in the IDE.

Ideally I would like a way to add the blogPlatform as a dependency to the blogUI project, such that it is respected by Eclipse and Play, and such that blogPlatform is rebuilt when blogUI is rebuilt. So, just adding a precompiled jar file to a lib directory in the Play project is not sufficient (another method which I came across but which I haven't tried).

Any suggestions or pointers towards tools or resources would be greatly appreciated!

I think this will mean setting up a custom multi project sbt build. I've been reading the sbt docs on multiproject builds, and found this question (stackoverflow.com/questions/9954272/…) but I still haven't quite got a handle on sbt and how to use it with Play... — Justin Lang

Alex Varju Alex Varju · Accepted Answer · 2013-08-06T17:35:45

If your two projects are tightly coupled, then a multi-project build probably makes the most sense. I found this blog post from fortytwo to be very helpful when setting up a multi-project build locally. When running play eclipse you should automatically end up with multiple Eclipse project files that have the correct dependencies.

If your projects are unrelated, externalized dependencies might make more sense. From your first project you can run play publish-local to deploy the jar files to your local Ivy repository; the sbt docs explain how to configure publishing to a central repository. From your second project, you can add a "groupId" % "artifactId" % "1.0-SNAPSHOT" dependency that points to this artifact. Unfortunately Eclipse doesn't play nicely with this configuration, and you have to manually replace the jarfile dependency with a project dependency after importing the two projects.

How to add dependency to Play framework project in Eclipse from second project?

1 Answers