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我有一张类似的桌子

final class FooTable(tag: Tag) extends Table[Foo](tag, "foo") {

  def id = column[Int]("id", O.PrimaryKey)

  def amount = column[Long]("amount")

  def createTs = column[Timestamp]("create_ts")

  def updateTs = column[Timestamp]("update_ts")

  def * = (id, amount, status, createTs, updateTs) <> (Foo.tupled, Foo.unapply)

}

并尝试检查TableQuery[FooTable].map{_.amount}.sum >= 10L结果是否为真，我想DBIO.seq在单个db.run.

到目前为止我已经尝试过

  val action = for {
    bar <- (foos.map{_.amount}.sum <= givenLongValue)
    result <- DBIO.seq("//some queries here") if bar
  } yield result

但这不起作用，因为这个错误

发现：slick.lifted.Rep[Boolean] 需要：布尔

我也试过这种方式

(fooes.map{_.amount}.sum <= amount).filter{_}.map{ x =>
      DBIO.seq("some actions")
}

但这也会产生错误

找不到参数 ol 的隐式值：slick.lifted.OptionLift[slick.driver.MySQLDriver.api.DBIOAction[Unit,slick.driver.MySQLDriver.api.NoStream,slick.driver.MySQLDriver.api.Effect.Write with slick .driver.MySQLDriver.api.Effect.Transactional],slick.lifted.Rep[Option[QO]]]

我怎样才能做到这一点？

提前致谢。

4

1 回答 1

1

您应该尝试以下方法：

val query = TableQuery[FooTable]
val givenLongValue = 10L
val action = query.map(_.amount).sum.result.flatMap {
  case Some(sum) if sum <= givenLongValue => DBIO.seq(...)
  case _ => DBIO.successful(...) // You should decide here what you want to return in case of `None` or `sum > 10L`
}.transactionally
于 2016-06-08T11:21:29.320 回答