MongoDB ObjectID as JSON using lift-json

Question

I'm using Bowler framework for some REST API's (internally uses lift-json module for heavy lifting) and have the following case class:

case class Item(_id : ObjectId, name : String, value : String)

When I return this case object back to client I need to include value for _id field. However, the _id column is being returned as an empty list in Json output instead of its actual value.

{"_id":{},"name":"Id Test","value":"id test"}

Any pointers on how this can be fixed will be greatly appreciated.

Update: I tried using custom serializer for it but for some reason it doesn't get called!

    class ObjectIdSerializer extends Serializer[ObjectId] {
    private val Class = classOf[ObjectId]

    def deserialize(implicit format: Formats) = {
      case (TypeInfo(Class, _), json) => json match {
        case JObject(JField("_id", JString(s)) :: Nil) => new ObjectId(s)
        case x => throw new MappingException("Can't convert " + x + " to  ObjectId")
      }
    }

    def serialize(implicit format: Formats) = {
      case x: ObjectId => { println("\t @@@@@@@@Custom Serializer was called!"); JObject(JField("_id", JString(x.toString)) :: Nil)}
    }
  }

  implicit val formats = DefaultFormats + new ObjectIdSerializer

Answer 1

This is fixed. Needed to define my own RenderStrategy class in order to override the formats declaration. This post has more details on it http://blog.recursivity.com/post/5433171352/how-bowler-does-rendering-maps-requests-to-objects