+ slick #1334 add DBIOAction.collect

slick-testkit/src/main/scala/com/typesafe/slick/testkit/tests/ActionTest.scala

@@ -144,4 +144,32 @@ class ActionTest extends AsyncTest[RelationalTestDB] {
        _ = result shouldBe 2
      } yield ()
    }

  def testCollect = {
    class T(tag: Tag) extends Table[Int](tag, u"t") {
      def a = column[Int]("a")

      def * = a
    }
    val ts = TableQuery[T]
    for {
      _ <- db.run {
        ts.schema.create >>
          (ts ++= Seq(2, 3, 1, 5, 4))
      }
      q1 = ts.sortBy(_.a).map(_.a).take(1)
      result <- db.run(q1.result.headOption.collect {
        case Some(a) => a
      })
      _ = result shouldBe 1
      _ = result shouldFail { _ =>
        val future = db.run(q1.result.headOption.collect {
          case None => ()
        })
        import scala.concurrent.duration.Duration
        import scala.concurrent.Await
        Await.result(future, Duration.Inf)
      }
    } yield ()
  }
}

slick/src/main/scala/slick/dbio/DBIOAction.scala

@@ -109,6 +109,13 @@ sealed trait DBIOAction[+R, +S <: NoStream, -E <: Effect] extends Dumpable {
  def withFilter(p: R => Boolean)(implicit executor: ExecutionContext): DBIOAction[R, NoStream, E] =
    flatMap(v => if(p(v)) SuccessAction(v) else throw new NoSuchElementException("Action.withFilter failed"))

  /** Transform the result of a successful execution of this action, if the given partial function is defined at that value,
    * otherwise, the result DBIOAction will fail with a `NoSuchElementException`.
    *
    * If this action fails, the resulting action also fails. */
  def collect[R2](pf: PartialFunction[R,R2])(implicit executor: ExecutionContext): DBIOAction[R2, NoStream, E] =
    map(r1 => pf.applyOrElse(r1,(r:R) => throw new NoSuchElementException(s"DBIOAction.collect partial function is not defined at: $r")))

  /** Return an action which contains the Throwable with which this action failed as its result.
    * If this action succeeded, the resulting action fails with a NoSuchElementException. */
  def failed: DBIOAction[Throwable, NoStream, E] = FailedAction[E](this)