SLICK如何定义用于案例类的双向一对多关系

Question

我正在使用SLICK 1.0.0-RC2.我已经定义了以下两个表Directorate和ServiceArea,其中Directorate与ServiceArea有一对多的关系

case class Directorate(dirCode: String, name: String)

object Directorates extends Table[Directorate]("DIRECTORATES") {

  def dirCode = column[String]("DIRECTORATE_CODE", O.PrimaryKey)

  def name = column[String]("NAME")

  def * = dirCode ~ name  <> (Directorate, Directorate.unapply _) 
}

case class ServiceArea(areaCode: String, dirCode: String, name: String)

object ServiceAreas extends Table[ServiceArea]("SERVICE_AREAS") {

  def areaCode = column[String]("AREAE_CODE", O.PrimaryKey)

  def dirCode = column[String]("DIRECTORATE_CODE")

  def name = column[String]("NAME")

  def directorate = foreignKey("DIR_FK", dirCode, Directorates)(_.dirCode)

  def * = areaCode ~ dirCode ~ name <> (ServiceArea, ServiceArea.unapply _)
}

为了使我的Play应用程序表单中的Directorate案例类有用,我试图重新定义Directorate案例类,以获得与该局相关的Seq of ServiceAreas.

case class Directorate(dirCode: String, name: String, serviceAreas: Seq[ServiceArea])

我的问题现在是Directorate表投影.我试图在Directorates中创建一个方法:

def serviceAreas = (for { a <- ServiceAreas
                         if (a.dirCode === dirCode)
                    } yield (a)).list map {
                      case t: ServiceArea => t
                    }

所以我可以尝试类似的东西

def * = dirCode ~ name  ~ serviceAreas <> (Directorate, Directorate.unapply _)

但这不能起作用,因为服务仅仅是一种方式.

对我而言,对于Directorate案例类来说,它是一个有用的域对象,它应该能够包含相关的ServiceAreas,这似乎是合理的.

我想知道如何遍历反向关系,以便Directorate表投影可以工作.

Answer 1

我确信有一个更优雅的解决方案,但这应该可以解决问题:

import scala.slick.driver.H2Driver.simple._
import Database.threadLocalSession

object SlickExperiments2 {

  Database.forURL("jdbc:h2:mem:test1", driver = "org.h2.Driver") withSession {

    (Directorates.ddl ++ ServiceAreas.ddl).create

    case class Directorate(dirCode: String, name: String) {
      def serviceAreas: Seq[ServiceArea] = (for {
        a <- ServiceAreas
        if (a.dirCode === dirCode)
      } yield (a)).list
    }

    object Directorates extends Table[Directorate]("DIRECTORATES") {

      def dirCode = column[String]("DIRECTORATE_CODE", O.PrimaryKey)

      def name = column[String]("NAME")

      def * = dirCode ~ name <> (Directorate, Directorate.unapply _)
    }

    case class ServiceArea(areaCode: String, dirCode: String, name: String)

    object ServiceAreas extends Table[ServiceArea]("SERVICE_AREAS") {

      def areaCode = column[String]("AREAE_CODE", O.PrimaryKey)

      def dirCode = column[String]("DIRECTORATE_CODE")

      def name = column[String]("NAME")

      def directorate = foreignKey("DIR_FK", dirCode, Directorates)(_.dirCode)

      def * = areaCode ~ dirCode ~ name <> (ServiceArea, ServiceArea.unapply _)
    }

    Directorates.insert(Directorate("Dircode", "Dirname"))

    ServiceAreas.insertAll(ServiceArea("a", "Dircode", "A"), ServiceArea("b", "Dircode", "B"))

    val sa = (for{
    d <- Directorates
    } yield d).list map { case t: Directorate => t.serviceAreas}

    println(sa)
  }                                              
 //> List(List(ServiceArea(a,Dircode,A), ServiceArea(b,Dircode,B)))
}