Scala 如何在lift'；谁是地图绘制者？

mapper是否允许在模型中创建复合键？如果是，请给出一个例子。

这是一个例子：

class FooBar extends LongKeyedMapper[FooBar] { 
  def getSingleton = FooBar 
  def primaryKeyField = id 
  object id extends MappedLongIndex(this) 
  object foo extends MappedLongForeignKey(this, Foo) 
  object bar extends MappedLongForeignKey(this, Bar) 
} 

object FooBar extends FooBar with LogKeyedMetaMapper[FooBar] { 
  override def dbIndexes = Index(foo, bar) :: super.dbIndexes 
} 

示例取自

这是一个示例：

class FooBar extends LongKeyedMapper[FooBar] { 
  def getSingleton = FooBar 
  def primaryKeyField = id 
  object id extends MappedLongIndex(this) 
  object foo extends MappedLongForeignKey(this, Foo) 
  object bar extends MappedLongForeignKey(this, Bar) 
} 

object FooBar extends FooBar with LogKeyedMetaMapper[FooBar] { 
  override def dbIndexes = Index(foo, bar) :: super.dbIndexes 
} 

示例取自最后一行中的“override def dbIndexes”。简单def dbIndexes将不起作用，最后一行中的“override def dbIndexes”。简单的def dbIndexes将不起作用