Lift Mapper或Record Framework中的继承

Question

有没有办法使用Mapper o Record Framework在Lift中定义适当的继承模型,其中有一个父类表和一个每个子表一个表？

Answer 1

假设你想使用继承来在每个子类中使用相同的映射字段,我通过对这些字段使用特征来解决这个问题:

trait SuperFields[T <: Mapper[T]] {
  self: T =>
  object DESCRIPTION extends MappedString[T](this, 255)
  object BRAND extends MappedString[T](this, 50)
  // etc
}

然后每个Mapper/MetaMapper将扩展SuperFields,但是定义他们自己的数据库表和连接标识符:

class Product extends Mapper[Product] with SuperFields[Product] {
  override def getSingleton = Product
}

object Product extends Product with MetaMapper[Product] {
  override def dbTableName = "PRODUCT"
  override def dbDefaultConnectionIdentifier = SomeConnection
}

和:

class Service extends Mapper[Service] with SuperFields[Service] {
  override def getSingleton = Service
}

object Service extends Service with MetaMapper[Service] {
  override def dbTableName = "SERVICE"
  override def dbDefaultConnectionIdentifier = SomeOtherConnection
}