【发布时间】：2014-07-27 04:54:15
【问题描述】：
假设您有以下代码，我在将具有 > 22 列的表专门映射到 case class 时遇到问题
import slick.driver.PostgresDriver
import scala.slick.collection.heterogenous._
import syntax._
import shapeless.Generic
case class TwentyThreeCaseClass(
val id:Option[Long],
val one:String,
val two:String,
val three:String,
val four:String,
val five:String,
val six:String,
val seven:String,
val eight:String,
val nine:String,
val ten:String,
val eleven:String,
val twelve:String,
val thirteen:String,
val fourteen:String,
val fifteen:String,
val sixteen:String,
val seventeen:String,
val eighteen:String,
val nineteen:String,
val twenty:String,
val twentyOne:String,
val twentyTwo:String,
val twentyThree:String,
val twentyFour:String
)
class TwentyThreeTable(tag:Tag) extends Table[TwentyThreeCaseClass](tag,"twenty_three_table") {
def id = column[Long]("id",O.PrimaryKey,O.AutoInc)
def one = column[String]("one")
def two = column[String]("two")
def three = column[String]("three")
def four = column[String]("four")
def five = column[String]("five")
def six = column[String]("six")
def seven = column[String]("seven")
def eight = column[String]("eight")
def nine = column[String]("nine")
def ten = column[String]("ten")
def eleven = column[String]("eleven")
def twelve = column[String]("twelve")
def thirteen = column[String]("thirteen")
def fourteen = column[String]("fourteen")
def fifteen = column[String]("fifteen")
def sixteen = column[String]("sixteen")
def seventeen = column[String]("seventeen")
def eighteen = column[String]("eighteen")
def nineteen = column[String]("nineteen")
def twenty = column[String]("twenty")
def twentyOne = column[String]("twentyOne")
def twentyTwo = column[String]("twentyTwo")
def twentyThree = column[String]("twentyThree")
def twentyFour = column[String]("twentyFour")
private def iso[L <: HList, M <: HList](l: L)
(implicit iso: Generic.Aux[TwentyThreeCaseClass, M], eq: L =:= M): TwentyThreeCaseClass = iso.from(l)
def * =
id.? ::
one ::
two ::
three ::
four ::
five ::
six ::
seven ::
eight ::
nine ::
ten ::
elven ::
twelve ::
thirteen ::
fourteen ::
fifteen ::
sixteen ::
seventeen ::
eighteen ::
nineteen ::
twenty ::
twentyOne ::
twentyTwo ::
twentyThree ::
twentyFour ::
HNil
// Do stuff here to map to a case class
}
您将如何将表构造/提取到TwentyThreeCaseClass 中。给出了如何将光滑的Table 映射到 HList 的示例代码，但没有给出关于如何通过 HList 将 Table 映射到案例类 > 22 个参数的代码（您不能使用元组，因为Scala 中的数量限制仍然适用于元组，你不能创建一个包含超过 22 个元素的元组）
iso 就在那里，因为我们使用这个通用的 iso 代码从 HList 映射到 case class，在我们的无形代码中具有相同的形状，所以理论上你应该能够使用iso 从HList 构造案例类，我只是不知道如何在光滑形状的上下文中使用iso
编辑： 在 slick github 上提出了与https://github.com/slick/slick/issues/519#issuecomment-48327043 中的问题相同的问题@
【问题讨论】：
标签： scala slick case-class shapeless