adding task to sbt 13.x build.sbt - scala

Question

I have added this to build.sbt
libraryDependencies += "com.typesafe.slick" %% "slick-codegen" % "2.1.0"
lazy val slickGenerate = TaskKey[Seq[File]]("slick code generation")
slickGenerate <<= slickGenerateTask
lazy val slickGenerateTask = {
(sourceManaged in Compile, dependencyClasspath in Compile, runner in Compile, streams) map { (dir, cp, r, s) =>
val dbName = "dbname"
val userName = "user"
val password = "password"
val url = s"jdbc:mysql://server:port/$dbName"
val jdbcDriver = "com.mysql.jdbc.Driver"
val slickDriver = "scala.slick.driver.MySQLDriver"
val targetPackageName = "models"
val outputDir = (dir / dbName).getPath // place generated files in sbt's managed sources folder
val fname = outputDir + s"/$targetPackageName/Tables.scala"
println(s"\nauto-generating slick source for database schema at $url...")
println(s"output source file file: file://$fname\n")
r.run("scala.slick.codegen.SourceCodeGenerator", cp.files, Array(slickDriver, jdbcDriver, url, outputDir, targetPackageName, userName, password), s.log)
Seq(file(fname))
}
}
The task's code itself isn't very exciting. It just needs to create an auto-generated scala source file. Problem is, sbt starts fine, yet this new task is evidently not recognized by sbt and cannot be run in the sbt prompt. I have also had very little luck with the := syntax for task definition. Existing documentation has been just confounding.
How can this new task be made available in the sbt prompt?

Answer 1

This works
libraryDependencies += "com.typesafe.slick" %% "slick-codegen" % "2.1.0"
lazy val slickGenerate = taskKey[Seq[File]]("slick code generation")
slickGenerate := {
val dbName = "dbname"
val userName = "user"
val password = "password"
val url = s"jdbc:mysql://server:port/$dbName"
val jdbcDriver = "com.mysql.jdbc.Driver"
val slickDriver = "scala.slick.driver.MySQLDriver"
val targetPackageName = "models"
val outputDir = ((sourceManaged in Compile).value / dbName).getPath // place generated files in sbt's managed sources folder
val fname = outputDir + s"/$targetPackageName/Tables.scala"
println(s"\nauto-generating slick source for database schema at $url...")
println(s"output source file file: file://$fname\n")
(runner in Compile).value.run("scala.slick.codegen.SourceCodeGenerator", (dependencyClasspath in Compile).value.files, Array(slickDriver, jdbcDriver, url, outputDir, targetPackageName, userName, password), streams.value.log)
Seq(file(fname))
}
In sbt 0.13.x you don't need all those blabla map sameblabla boilerplates. Just access value as is (runner in Compile).value - macro will do everything else for you.
> slickGenerate
[info] Updating {file:/Users/user/slick/}slick...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
auto-generating slick source for database schema at jdbc:mysql://server:port/dbname...
output source file file: file:///Users/user/slick/target/scala-2.10/src_managed/main/dbname/models/Tables.scala
> help slickGenerate
slick code generation
Talking about <<= - your TaskKey is incorrect, see the definition:
def apply[T](label : scala.Predef.String, description : scala.Predef.String // not description
So, the old definition <<= uses "generate slick code" as label, while the new := uses the code-given name for command (new style), so it uses your "generate slick code" as a doc. Which looks strange and inconsistent, but that's a fact and it's partially reasoned by backward-compatibility.
So, correct old-style version is:
import sbt.Keys._
lazy val slickGenerate = TaskKey[Seq[File]]("slick-generate", "generate slick code")
slickGenerate <<= slickGenerateTask
def slickGenerateTask =
(sourceManaged in Compile, dependencyClasspath in Compile, runner in Compile, streams) map { (dir, cp, r, s) =>
...
}
It works in the same way as previous. Note, that you have to use "slickGenerate", not "slick-generate", the last one doesn't work for "help" command.
By the way, you're using Bare build definition now - you may want to switch to Multi-project .sbt definition as it's recommended by sbt docs, see also.