Runtime exception compiling query containing groupBy(x=>x)

[ianba]

I am trying to use the pattern query.groupBy(x=>x).map(_._1) to simulate a SELECT DISTINCT; however, I am hitting a runtime exception in some situations.

This pattern works if query is a TableQuery. A similar query of the form query.groupBy(_.*).map(_._1) works as expected. However, more generic queries of the form query.groupBy(x=>x).map(_._1) crash with the error:

scala.slick.SlickException: No type for symbol s2 found in {id: Int/INTEGER, a: Int/INTEGER}

I'm using the lastest milestone: 2.0.0-M3.

Example code demonstrating the issue:

import scala.slick.driver.JdbcDriver.simple._
object Test {
  class Test(tag: Tag) extends Table[(Int, Int)](tag, "test") {
    def id = column[Int]("id")
    def a = column[Int]("a")
    def * = (id, a)
  }

  val test = TableQuery[Test]

  val q1 = test.groupBy(x => x).map(_._1)
  val q2 = test.map(x => x).groupBy(_.*).map(_._1)
  val q3 = test.map(x => x).groupBy(x => x).map(_._1)
}

scala> Test.q1.selectStatement
res0: String = select x2."id", x2."a" from "test" x2 group by x2."id", x2."a"

scala> Test.q2.selectStatement
res1: String = select x2."id", x2."a" from "test" x2 group by x2."id", x2."a"

scala> Test.q3.selectStatement
scala.slick.SlickException: No type for symbol s2 found in {id: Int/INTEGER, a: Int/INTEGER}
    at scala.slick.ast.Type$class.select(Type.scala:19)
    at scala.slick.ast.StructType.scala$slick$ast$StructType$$super$select(Type.scala:42)
    at scala.slick.ast.StructType$$anonfun$select$3.apply(Type.scala:42)
    at scala.slick.ast.StructType$$anonfun$select$3.apply(Type.scala:42)
    at scala.Option.getOrElse(Option.scala:120)
    at scala.slick.ast.StructType.select(Type.scala:42)
    at scala.slick.ast.Select.buildType(Node.scala:466)
    at scala.slick.ast.SimplyTypedNode$class.nodeWithComputedType2(Node.scala:124)
    at scala.slick.ast.Select.nodeWithComputedType2(Node.scala:457)
    at scala.slick.ast.Select.nodeWithComputedType2(Node.scala:457)
    at scala.slick.ast.Node$class.nodeWithComputedType(Node.scala:110)
    at scala.slick.ast.Select.nodeWithComputedType(Node.scala:457)
    at scala.slick.ast.SimplyTypedNode$$anonfun$4.apply(Node.scala:123)
    at scala.slick.ast.SimplyTypedNode$$anonfun$4.apply(Node.scala:123)
    at scala.slick.ast.Util$$anonfun$mapOrNone$1.apply(Util.scala:15)
    at scala.slick.ast.Util$$anonfun$mapOrNone$1.apply(Util.scala:14)
    at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
    at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
    at scala.slick.ast.Util$.mapOrNone(Util.scala:14)
    at scala.slick.ast.Node$class.nodeMapChildren(Node.scala:42)
    at scala.slick.ast.StructNode.nodeMapChildren(Node.scala:187)
    at scala.slick.ast.SimplyTypedNode$class.nodeWithComputedType2(Node.scala:123)
    at scala.slick.ast.StructNode.nodeWithComputedType2(Node.scala:187)
    at scala.slick.ast.StructNode.nodeWithComputedType2(Node.scala:187)
    at scala.slick.ast.Node$class.nodeWithComputedType(Node.scala:110)
    at scala.slick.ast.StructNode.nodeWithComputedType(Node.scala:187)
    at scala.slick.ast.SimplyTypedNode$$anonfun$4.apply(Node.scala:123)
    at scala.slick.ast.SimplyTypedNode$$anonfun$4.apply(Node.scala:123)
    at scala.slick.ast.Util$$anonfun$mapOrNone$1.apply(Util.scala:15)
    at scala.slick.ast.Util$$anonfun$mapOrNone$1.apply(Util.scala:14)
    at scala.collection.immutable.List.foreach(List.scala:318)
    at scala.slick.ast.Util$.mapOrNone(Util.scala:14)
    at scala.slick.ast.Node$class.nodeMapChildren(Node.scala:42)
    at scala.slick.ast.Pure.nodeMapChildren(Node.scala:256)
    at scala.slick.ast.SimplyTypedNode$class.nodeWithComputedType2(Node.scala:123)
    at scala.slick.ast.Pure.nodeWithComputedType2(Node.scala:256)
    at scala.slick.ast.Pure.nodeWithComputedType2(Node.scala:256)
    at scala.slick.ast.Node$class.nodeWithComputedType(Node.scala:110)
    at scala.slick.ast.Pure.nodeWithComputedType(Node.scala:256)
    at scala.slick.ast.Bind.nodeWithComputedType2(Node.scala:428)
    at scala.slick.ast.Bind.nodeWithComputedType2(Node.scala:416)
    at scala.slick.ast.Node$class.nodeWithComputedType(Node.scala:110)
    at scala.slick.ast.Bind.nodeWithComputedType(Node.scala:416)
    at scala.slick.ast.Bind.nodeWithComputedType2(Node.scala:426)
    at scala.slick.ast.Bind.nodeWithComputedType2(Node.scala:416)
    at scala.slick.ast.Node$class.nodeWithComputedType(Node.scala:110)
    at scala.slick.ast.Bind.nodeWithComputedType(Node.scala:416)
    at scala.slick.ast.ResultSetMapping.nodeWithComputedType2(ClientSideOp.scala:52)
    at scala.slick.ast.ResultSetMapping.nodeWithComputedType2(ClientSideOp.scala:42)
    at scala.slick.ast.Node$class.nodeWithComputedType(Node.scala:110)
    at scala.slick.ast.ResultSetMapping.nodeWithComputedType(ClientSideOp.scala:42)
    at scala.slick.compiler.AssignTypes$$anonfun$apply$1.apply(AssignTypes.scala:10)
    at scala.slick.compiler.AssignTypes$$anonfun$apply$1.apply(AssignTypes.scala:10)
    at scala.slick.compiler.CompilerState.map(QueryCompiler.scala:144)
    at scala.slick.compiler.AssignTypes.apply(AssignTypes.scala:10)
    at scala.slick.compiler.QueryCompiler$$anonfun$runPhase$1.apply(QueryCompiler.scala:55)
    at scala.slick.compiler.QueryCompiler$$anonfun$runPhase$1.apply(QueryCompiler.scala:54)
    at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
    at scala.slick.ast.SymbolNamer.use(Symbol.scala:101)
    at scala.slick.compiler.QueryCompiler.runPhase(QueryCompiler.scala:54)
    at scala.slick.compiler.QueryCompiler$$anonfun$run$2.apply(QueryCompiler.scala:46)
    at scala.slick.compiler.QueryCompiler$$anonfun$run$2.apply(QueryCompiler.scala:46)
    at scala.collection.TraversableOnce$$anonfun$foldLeft$1.apply(TraversableOnce.scala:144)
    at scala.collection.TraversableOnce$$anonfun$foldLeft$1.apply(TraversableOnce.scala:144)
    at scala.collection.Iterator$class.foreach(Iterator.scala:727)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
    at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
    at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
    at scala.collection.TraversableOnce$class.foldLeft(TraversableOnce.scala:144)
    at scala.collection.AbstractTraversable.foldLeft(Traversable.scala:105)
    at scala.slick.compiler.QueryCompiler.run(QueryCompiler.scala:46)
    at scala.slick.compiler.QueryCompiler.run(QueryCompiler.scala:41)
    at scala.slick.profile.BasicProfile$Implicits$class.queryToQueryExecutor(BasicProfile.scala:44)
    at scala.slick.driver.JdbcProfile$$anon$1.queryToQueryExecutor(JdbcProfile.scala:21)

[szeiger]

Cannot reproduce. This works for me in M3.

[ianba]

Hmmm... the above code definitely throws the above exception for me with the following build.sbt:

scalaVersion := "2.10.3"

libraryDependencies += "com.typesafe.slick" %% "slick" % "2.0.0-M3"

[nafg]

Maybe a self-contained github project that demonstrates the issue would
help?

On Thu, Dec 12, 2013 at 9:27 AM, Ian Baker notifications@github.com wrote:

Hmmm... the above code definitely throws the above exception for me with
the following build.sbt:

scalaVersion := "2.10.3"

libraryDependencies += "com.typesafe.slick" %% "slick" % "2.0.0-M3"

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/252#issuecomment-30426109
.

[ianba]

Ok, I copied the code above into a test case in the slick testkit. The test fails at both 2.0.0-M3 and HEAD. Please take a look.

[papauschek]

Having the same issue after upgrading from slick 1.0.1. The same query works in Slick 1. Is there a workaround compatible with Slick 2?

I'm also curious as to why this issue is postponed until Slick 2.1? Looks like a regression to me.

[szeiger]

I wasn't aware that this is a regression. I assume that #565 will fix it but that PR caused other problems so it needs some more work for 2.0.1.

[papauschek]

Thanks for the quick response, looking forward to the next release.

[szeiger]

GroupBy fixes have been merged for 2.0.1. Closing.