Extract Data from MongoDBList

Question

How can I get a List(String) from this MongoDBList?

val a: MongoDBList = ... // equal to [ { "id" : "0001"} , { "id" : "0017"}]

Desired result: List("0001", "0017")

David Holbrook · Answer 1 · 2013-09-09T18:54:18.983

0

MongoDBList extends scala.collection.mutable.LinearSeq so you should be able to to use toList

val bld = MongoDBList.newBuilder

bld += MongoDBObject("id" -> "0001")
bld += MongoDBObject("id" -> "0017")

val a = bld.result

val l = for( o <- a.toList )
  yield JSON.parse(o.toString).asInstanceOf[DBObject].get("id")

println(l)

//output
//List(0001, 0017)

edited Sep 09 '13 at 18:54

answered Sep 08 '13 at 16:39

David Holbrook

1,617
14
18

Hi David - when I try that, I get `List({ "id" : "0001"}, { "id" : "0017"})`. After getting this result, I suppose I need to convert each item to a `JsValue`, and then parse via `val idVal = (listElementJson \ "id").asOpt[String]`? – Kevin Meredith Sep 09 '13 at 13:37
I didn't quite follow what you were asking, answer is updated to reflect actual question – David Holbrook Sep 09 '13 at 18:54

score 0 · Answer 2 · answered Dec 31 '14 at 09:23

I would prefer:

val bld = MongoDBList.newBuilder

bld += MongoDBObject("id" -> "0001")
bld += MongoDBObject("id" -> "0017")

val a = bld.result

a.map(x=> x.asInstanceOf[DBObject].getAs[String]("id").get)
// or to avoid nonexitence emelents
a.flatMap(x=> x.asInstanceOf[DBObject].getAs[String]("id"))

I don't like asInstanceOf here if you have

{ "data" : [ { "id" : "0001"} , { "id" : "0017"}] }

casbash can serialize Seq for you

val a2 = MongoDBObject( "data" -> a )
a2.getAs[Seq[DBObject]]("aa").get.map { x => x.getAs[String]("id").get}

Extract Data from MongoDBList

2 Answers2