Question

我正在使用scala play 2，slick和postgresql作为数据库。我的一个功能就像

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)))
}

此代码无效。创建问题并更新客户的属性。即customer.created和customer.updated是Rep [Option [Instant]]，即日期时间。如果我从那两列（customer.created和customer.updated）中逃脱，那么它没问题。那是

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)))
}

此代码工作正常。我想将Rep [Option [Instant]]转换为Rep [Option [String]]。我怎么能这样做？

Answer 1

光滑需要Mapping custom types到已知jdbc types。在您的案例中，为DateTime到Timestamp或Instant到Timestamp的光滑提供隐式映射。这有助于slick根据custom types了解native database supported types。

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

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

如果是即时类型

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)))

Slick Implicit for java.time.Instant

import java.sql.Timestamp

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

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

1 个答案: