Adding overloaded sequence method for Option, simple test - #1192

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

@@ -1,6 +1,8 @@
package com.typesafe.slick.testkit.tests

import com.typesafe.slick.testkit.util.{StandardTestDBs, RelationalTestDB, AsyncTest}
import com.typesafe.slick.testkit.util.{AsyncTest, RelationalTestDB, StandardTestDBs}
import slick.dbio.DBIOAction
import slick.dbio.Effect.Read

import scala.collection.mutable.ArrayBuffer
import scala.concurrent.Future
@@ -110,6 +112,30 @@ class ActionTest extends AsyncTest[RelationalTestDB] {
    )
  } else DBIO.successful(())

  def testOptionSequence = {
    class T(tag: Tag) extends Table[Option[Int]](tag, u"t") {
      def a = column[Int]("a")
      def * = a.?
    }
    val ts = TableQuery[T]

    val aSetup = ts.schema.create

    val a1 = LiteralColumn(Option(1)).result
    val a2 = DBIO.sequence(Option(LiteralColumn(1).result))
    val a3 = DBIO.sequence(Option.empty[DBIO[Int]])

    for {
      _ <- aSetup
      b1 <- a1
      b2 <- a2
      b3 <- a3
    } yield {
      b1 shouldBe b2
      b2 shouldNotBe b3
    }
  }

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

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

@@ -170,6 +170,12 @@ object DBIOAction {
    total.result()
  }

  /** Transform a `Option[ DBIO[R] ]` into a `DBIO[ Option[R] ]`. */
  def sequence[R, E <: Effect](in: Option[DBIOAction[R, NoStream, E]]): DBIOAction[Option[R], NoStream, E] = {
    implicit val ec = DBIO.sameThreadExecutionContext
    sequence(in.toList).map(_.headOption)
  }

  /** Transform a `TraversableOnce[ DBIO[R] ]` into a `DBIO[ TraversableOnce[R] ]`. */
  def sequence[R, M[+_] <: TraversableOnce[_], E <: Effect](in: M[DBIOAction[R, NoStream, E]])(implicit cbf: CanBuildFrom[M[DBIOAction[R, NoStream, E]], R, M[R]]): DBIOAction[M[R], NoStream, E] = {
    implicit val ec = DBIO.sameThreadExecutionContext