Question

我想从Casbah的MongoCollectionBase.find（...）返回的DBObject中提取某个键的值，在这种情况下为“orderItems”。我有解决方案，但我不满意。我发现我的解决方案很麻烦。它在每一步都将从DBObject.toMap返回的java.util.Map转换为Scala Map或其他集合。有什么更好的方法呢？感谢

val orders = provisioningDb("systems").find(MongoDBObject.empty, MongoDBObject("company.department.orders" -> 1))

import scala.collection.JavaConversions._

def findC(m : Map[String, Any]) : Iterable[Any] = {
  val c = for ((k, v) <- m) yield (k, v) match {
    case (k, v) if k equals "orderItems" => v
    case (k, v : java.util.HashMap[String, Any]) => findC(toMap(v).asInstanceOf[Map[String, Any]]).head
    case _ => Nil
  }
  c.filter(_.isInstanceOf[java.util.List[Any]] )
}

def toMap[K, E](m: java.util.Map[K, E]): Map[K, E] = {
  Map.empty ++ new MapWrapper[K, E](m)
}

val orderItems = for {
  x <- orders
} yield x

for (y <- orderItems) {
  println(findC(toMap(y.toMap).asInstanceOf[Map[String, Any]]))
}

删除了详细信息的2行示例数据，这些数据在MongoDB中保留，

company : {department : {orders -> [{"id" : "543", "quantity" : 2}, {"id" : "223", "quantity" : 21}, {"id" : "332", "quantity" : 3}] 


company : {department : {orders -> [{"id" : "222", "quantity" : 8}, {"id" : "663", "quantity" : 3]

Answer 1

您是否尝试过使用case class以及Salat？

您还可以查看这个精彩的presentation，特别是幻灯片#28，它会讨论SalatDAO，它允许您直接保留并检索您的案例对象！

使用Scala / Casbah从MongoDB DBObject中提取值

1 个答案: