如何將MongoDBList轉換爲BasicDBList？

Question

我使用Casbah 2.5.0。有教程中的例子：

scala> val builder = MongoDBList.newBuilder 
scala> builder += "foo" 
scala> builder += "bar" 
scala> builder += "x" 
scala> builder += "y" 
builder.type = com.mongodb.casbah.commons.MongoDBListBuilder@... 

scala> val newLst = builder.result 
newLst: com.mongodb.BasicDBList = [ "foo" , "bar" , "x" , "y"] 

所以newLst這裏是BasicDBList。

但是，當我自己嘗試它時，它的工作方式不同。

scala> val builder = MongoDBList.newBuilder 
scala> builder += "foo" 
scala> builder += "bar" 
scala> val newLst = builder.result 
newLst: com.mongodb.casbah.commons.MongoDBList = [ "foo" , "bar"] 

newLst這裏的類型是MongoDBList。

這是爲什麼？我如何將MongoDBList轉換爲BasicDBList？

Answer 1

有從com.mongodb.casbah.commons.MongoDBList到com.mongodb.BasicDBList在卡斯巴的隱式轉換（檢查com.mongodb.casbah.commons.Implicits）：

implicit def unwrapDBList(in: MongoDBList): BasicDBList = in.underlying 

只是通過MongoDBList到位置BasicDBList預計：

scala> val l: BasicDBList = newLst 
l: com.mongodb.casbah.Imports.BasicDBList = [ "foo" , "bar"] 

如果你想創建MongoDBList from List：

scala> val list = List("foo", "bar") 
list: List[java.lang.String] = List(foo, bar) 

scala> val dbList = MongoDBList(list:_*) 
dbList: com.mongodb.casbah.commons.MongoDBList = [ "foo" , "bar"]