映射列类型SLICK 3.1.1 [英] Mapping column types Slick 3.1.1

问题描述

我是SLICK新手，很难将java.sql.date/time/Timestamp的映射映射到jodatime。

trait ColumnTypeMappings {

  val profile: JdbcProfile
  import profile.api._

  val localTimeFormatter = DateTimeFormat.forPattern("HH:mm:ss")
  val javaTimeFormatter = new SimpleDateFormat("HH:mm:ss")

  implicit val myDateColumnType = MappedColumnType.base[LocalDate, Date](
    ld => new        java.sql.Date(ld.toDateTimeAtStartOfDay(DateTimeZone.UTC).getMillis),
    d  => new LocalDateTime(d.getTime).toLocalDate
  )

  implicit val myTimeColumnType = MappedColumnType.base[LocalTime, Time](
    lt => new java.sql.Time(javaTimeFormatter.parse(lt.toString(localTimeFormatter)).getTime),
    t  => new LocalTime(t.getTime)
  )

  implicit val myTimestampColumnType = MappedColumnType.base[DateTime, Timestamp](
    dt => new java.sql.Timestamp(dt.getMillis),
    ts => new DateTime(ts.getTime, DateTimeZone.UTC)
  )

}

在自动生成的Tables.scala中，我包含如下映射：

trait Tables extends ColumnTypeMappings {
  val profile: slick.driver.JdbcDriver
  import profile.api._
  import scala.language.implicitConversions
  // + rest of the auto generated code by slick codegen
}

作为总结，我是这样使用的：

object TestTables extends Tables {
  val profile = slick.driver.MySQLDriver
}

import Tables._
import profile.api._

val db = Database.forURL("url", "user", "password", driver = "com.mysql.jdbc.Driver")
val q = Company.filter(_.companyid === 1).map(._name)
val action = q.result
val future = db.run(action)
val result = Await.result(future, Duration.Inf)

我在上遇到NullPointerException：IMPLICIT Val myDateColumnType...在运行此程序时。我已验证如果删除映射，最后一段代码可以正常工作。

推荐答案

尝试在MappedColumnTypes的定义中将implicit val更改为implicit def。原因与Maksym Chernenko对question给出的答案有关。通常，JdbcProfile驱动程序(定义api.MappedColumnType)尚未注入，并且：

这会导致NPE。您可以设置"mapper"vallazy，也可以更改它 从val到def(如下所示)

implicit def myDateColumnType = MappedColumnType.base[LocalDate, Date](
  ld => new java.sql.Date(ld.toDateTimeAtStartOfDay(DateTimeZone.UTC).getMillis),
  d  => new LocalDateTime(d.getTime).toLocalDate
)

implicit def myTimeColumnType = MappedColumnType.base[LocalTime, Time](
  lt => new java.sql.Time(javaTimeFormatter.parse(lt.toString(localTimeFormatter)).getTime),
  t  => new LocalTime(t.getTime)
)

implicit def myTimestampColumnType = MappedColumnType.base[DateTime,  Timestamp](
  dt => new java.sql.Timestamp(dt.getMillis),
  ts => new DateTime(ts.getTime, DateTimeZone.UTC)
)

这篇关于映射列类型SLICK 3.1.1的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！