scaladoc - Can I use sbt's `apiMappings` setting for managed dependencies?

Question

I'd like the ScalaDoc I generate with sbt to link to external libraries, and in sbt 0.13 we have autoAPIMappings which is supposed to add these links for libraries that declare their apiURL. In practice though, none of the libraries I use provide this in their pom/ivy metadata, and I suspect some of these libraries will never do so.

The apiMappings setting is supposed to help with just that, but it is typed as Map[File, URL] and hence geared towards setting doc urls for unmanaged dependencies. Managed dependencies are declared as instances of sbt.ModuleID and cannot be inserted directly in that map.

Can I somehow populate the apiMappings setting with something that will associate an URL with a managed dependency ?

A related question is: does sbt provide an idiomatic way of getting a File from a ModuleID? I guess I could try to evaluate some classpaths and get back Files to try and map them to ModuleIDs but I hope there is something simpler.

Note: this is related to https://stackoverflow.com/questions/18747265/sbt-scaladoc-configuration-for-the-standard-library/18747266, but that question differs by linking to the scaladoc for the standard library, for which there is a well known File scalaInstance.value.libraryJar, which is not the case in this instance.

Answer 1

I managed to get this working for referencing scalaz and play by doing the following:

apiMappings ++= {
  val cp: Seq[Attributed[File]] = (fullClasspath in Compile).value
  def findManagedDependency(organization: String, name: String): File = {
    ( for {
        entry <- cp
        module <- entry.get(moduleID.key)
        if module.organization == organization
        if module.name.startsWith(name)
        jarFile = entry.data
      } yield jarFile
    ).head
  }
  Map(
      findManagedDependency("org.scalaz",        "scalaz-core") -> url("https://scalazproject.ci.cloudbees.com/job/nightly_2.10/ws/target/scala-2.10/unidoc/")
    , findManagedDependency("com.typesafe.play", "play-json")   -> url("http://www.playframework.com/documentation/2.2.1/api/scala/")
  )
}

YMMV of course.