Slick 3 java.time.LocalDate 映射

Question

我使用的是 Slick 3.1.0，需要保留 java.time.LocalDate 类型的字段。

我有模型类：

case class Position(companyName: String, title: String, startDate: Option[LocalDate], endDate: Option[LocalDate], positionId: Option[Int] = None)

还有如下映射：

private[PositionTable] class PositionTable(tag: Tag) extends Table[Position](tag, "POSITIONS")  {
    val positionId = column[Int]("POSITION_ID", O.PrimaryKey, O.AutoInc)
    val companyName = column[String]("COMPANY_NAME")
    val title = column[String]("TITLE")
    val startDate = column[Date]("START_DATE")
    val endDate = column[Date]("END_DATE")
    def * = (companyName, title, startDate, endDate, positionId.?) <>(Position.tupled, Position.unapply)
}

如何在数据库中映射 startDate 和 endDate 字段以用 DATE 类型表示？

列映射器中 NullPointerException 的堆栈跟踪：

java.lang.NullPointerException
    at com.tiedin.repo.PositionTable$class.$init$(PositionRepository.scala:54)
    at repo.PositionRepositoryTest.<init>(PositionRepositoryTest.scala:13)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at java.lang.Class.newInstance(Class.java:442)
    at org.scalatest.tools.Runner$.genSuiteConfig(Runner.scala:1422)
    at org.scalatest.tools.Runner$$anonfun$31.apply(Runner.scala:1236)
    at org.scalatest.tools.Runner$$anonfun$31.apply(Runner.scala:1235)
    at scala.collection.immutable.List.map(List.scala:273)
    at org.scalatest.tools.Runner$.doRunRunRunDaDoRunRun(Runner.scala:1235)
    at org.scalatest.tools.Runner$$anonfun$runOptionallyWithPassFailReporter$2.apply(Runner.scala:1011)
    at org.scalatest.tools.Runner$$anonfun$runOptionallyWithPassFailReporter$2.apply(Runner.scala:1010)
    at org.scalatest.tools.Runner$.withClassLoaderAndDispatchReporter(Runner.scala:1500)
    at org.scalatest.tools.Runner$.runOptionallyWithPassFailReporter(Runner.scala:1010)
    at org.scalatest.tools.Runner$.run(Runner.scala:850)
    at org.scalatest.tools.Runner.run(Runner.scala)
    at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.runScalaTest2(ScalaTestRunner.java:138)
    at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.main(ScalaTestRunner.java:28)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)

Answer 1

步骤：

1. 定义隐式MappedColumnType
2. 将PositionTable 中的Date 类型更改为Option[LocalDate]。从您的模型类来看，我猜 startDate 和 endDate 可以为空。如果不是，请省略Option。
3. 大功告成

示例：

import java.sql.Date
import java.time.LocalDate
// other imports

class SomeDbClass {
  implicit val localDateToDate = MappedColumnType.base[LocalDate, Date](
    l => Date.valueOf(l),
    d => d.toLocalDate
  )

  private[PositionTable] class PositionTable(tag: Tag) extends Table[Position](tag, "POSITIONS")  {
    val positionId = column[Int]("POSITION_ID", O.PrimaryKey, O.AutoInc)
    val companyName = column[String]("COMPANY_NAME")
    val title = column[String]("TITLE")
    val startDate = column[Option[LocalDate]]("START_DATE")
    val endDate = column[Option[LocalDate]]("END_DATE")
    def * = (companyName, title, startDate, endDate, positionId.?) <>(Position.tupled, Position.unapply)
  }
}

当然，您可以将自定义映射列类型提取到特征中，然后在其他数据库类中重用它们。

延伸阅读：Using Custom Scalar Types in Queries