如何在 Scala 中将 Rep[Option[Instant]] 转换为 Rep[Option[String]]

Question

我正在使用 scala play 2、slick 和 postgresql 作为数据库。我的功能之一是

def getAllCustomersWithAccount: Future[Seq[CustomerDetail]] = {
val joinException = for {
  (customer, account) <- table join accountTable on (_.id === _.id)
} yield (customer.id, account.name, account.phone, account.email, customer.status, customer.balance, customer.payable, customer.created, customer.updated)

val result = db.run(joinException.result)
result.map(row => row.map(x => CustomerDetail(x._1, x._2, x._3, x._4, x._5, x._6, x._7, x._8, x._9)))
}

此代码不起作用。问题是创建和更新客户的属性。也就是说 customer.created 和 customer.updated 是 Rep[Option[Instant]] ，它是日期时间。如果我转义这两列（customer.created 和 customer.updated），那就没问题了。那就是

def getAllCustomersWithAccount: Future[Seq[CustomerDetail]] = {
    val joinException = for {
      (customer, account) <- table join accountTable on (_.id === _.id)
    } yield (customer.id, account.name, account.phone, account.email, customer.status, customer.balance, customer.payable)
    val result = db.run(joinException.result)
    result.map(row => row.map(x => CustomerDetail(x._1, x._2, x._3, x._4, x._5, x._6, x._7)))
}

此代码运行良好。我想将 Rep[Option[Instant]] 转换为 Rep[Option[String]]。我该怎么做？

Answer 1

Slick 需要从 custom types 到已知 jdbc types 的 Mapping。在您的情况下，为光滑提供从 DateTime 到 Timestamp 或 Instant 到 Timestamp 的隐式映射。这有助于slick从native database supported types 的角度理解custom types。

implicit def jodaTimeMapping: BaseColumnType[DateTime] = MappedColumnType.base[DateTime, Timestamp](
dateTime => new Timestamp(dateTime.getMillis),
timeStamp => new DateTime(timeStamp.getTime))

以上implicit 帮助Slick 将DateTime 转换为Timestamp，反之亦然。

Instant类型的情况

假设Instant 是DateTime 的包装器

case class Instant(time: DateTime)

implicit def instantMapping: BaseColumnType[Instant] = MappedColumnType.base[Instant, Timestamp](
instant => new Timestamp(instant.time.getMillis),
timeStamp => Instant(new DateTime(timeStamp.getTime)))

java.time.Instant 的 Slick 隐式映射

import java.sql.Timestamp

implicit def instantMapping: BaseColumnType[Instant] = MappedColumnType.base[Instant, Timestamp](
instant => new Timestamp(instant.toEpochMilli),
timeStamp => Instant.ofEpochMilli(timeStamp.getTime))