How to get the dependencies of all sub-projects from a SBT project, in a SBT task? - scala

Question

I'm write a SBT task, which can output the dependencies information, grouped by project (say a SBT project has multi projects)
I know there is a sbt-dependency-graph plugin, but I can use it directly, because I want to generate a json file, but that plugin just output the dependency tree to console, without returning an data object, I can't easily get the data I want.
I found the update task returns a UpdateReport which contains a lot of information I want, but it only belong to the current project. In command line, if I want to know the information of all project, I can manually show all the projects by projects command, and view them one by one by someproject/update.
But how to do the same in a SBT task? I tried:
val reports = projects.toList.map(prj => (update in prj).value)
It reports:
[error] /Users/me/workspace/sbt-test/project/Build.scala:51: Illegal dynamic reference: prj
[error] val reports = projects.toList.map(prj => (update in prj).value)
[error] ^
[error] one error found
How to fix it?
More code:
import sbt._
import sbt.Keys._
object DemoBuild extends Build {
lazy val allUpdate = taskKey[Unit]("show update reports of all projects")
lazy val core = project
lazy val web = project
lazy val allUpdateDef = allUpdate := {
val reports = projects.toList.map(prj => (update in prj).value)
println(reports)
}
lazy val root = (project in file("."))
.settings(
allUpdateDef
)
}

Answer 1

After checking the document: http://www.scala-sbt.org/0.13/docs/Tasks.html, I found the solution:
import sbt._
import sbt.Keys._
object DemoBuild extends Build {
lazy val groupByProject: Def.Initialize[Task[(String, UpdateReport)]] =
Def.task {
(thisProject.value.id, (update in thisProject).value)
}
lazy val filter = ScopeFilter(inAnyProject, inAnyConfiguration)
updateByProject := {
val subProjects = groupByProject.all(filter).value.map { case ( projectName, updateReport) =>
...
}
}
}