Question

我试图将一个案例类隐式转换为另一个案例类，但无法使代码生效。我的编辑给了我Seq [LegacyPhase]没有转换到预期的Seq [Phase]的错误。任何人都能指出我的方向吗？提前谢谢！

implicit def legacyToDashboardBrand(brand: LegacyDashboardBrand)(implicit session: Session): DashboardBrand = {
  val phaseSeq: Seq[Phase] = (for { phaseDataset <- dashboardPhasesQ if phaseDataset.brandId === brand.id
  } yield phaseDataset).list.toSeq
  DashboardBrand(id = brand.id, projectId = brand.projectId, name = brand.name, currentPhase = brand.currentPhase, phases = phaseSeq)
}

implicit def legacyToDashboardPhase(phase: LegacyPhase): Phase = {
  Phase(id = phase.id, brandId = phase.brandId, title = phase.title, steps = Seq())
}

编辑：如果我在第一个隐式转换定义中执行第二个隐式转换行，它就可以工作。

implicit def legacyToDashboardBrand(brand: LegacyDashboardBrand)(implicit session: Session): DashboardBrand = {
  val legacyPhaseSeq = (for { 
    phaseDataset <- dashboardPhasesQ if phaseDataset.brandId === brand.id
  } yield phaseDataset).list.toSeq
  val phaseSeq: Seq[Phase] = legacyPhaseSeq.map(phase => 
    Phase(id = phase.id, brandId = phase.brandId, title = phase.title, steps = Seq())
  )

  DashboardBrand(id = brand.id, projectId = brand.projectId, name = brand.name, currentPhase = brand.currentPhase, phases = phaseSeq)
}

Answer 1

您的第二个解决方案（包含重复的代码）有效，因为您明确地将Seq[LegacyPhase]转换为Seq[Phase]。

您可以通过在legacyToDashboardBrand转换函数的第一个LegacyPhase => Phase函数中添加隐式参数来获得相同的结果：

implicit def legacyToDashboardBrand(
  brand: LegacyDashboardBrand
)(implicit 
  session: Session,
  phaseConv: LegacyPhase => Phase
): DashboardBrand = {
  val phaseSeq: Seq[Phase] = (for { 
    phaseDataset <- dashboardPhasesQ if phaseDataset.brandId === brand.id
  } yield phaseDataset).list.map(phaseConv).toSeq
  DashboardBrand(
    id = brand.id, projectId = brand.projectId, name = brand.name,
    currentPhase = brand.currentPhase, phases = phaseSeq
  )
}

这样，您的LegacyDashboardBrand => DashboardBrand转换功能会使用您的LegacyPhase => Phase转化功能。

注意：我不认为在隐式转换函数中查询数据库是个好主意。隐式转换本身就非常“神奇”，并且使您的代码更难以理解，添加查询数据库等副作用只会使其变得更加神奇。

案例类隐式转换问题

1 个答案: