Problem with nested custom objects

[shenghuang]

Good afternoon Stéphane,

I am following your examples and they are great. However, I cannot make nested object works with 0.8.

I'm trying to store a nested document in MongoDB through Scala. The document looks like:
Project {
"_id": ObjectId("528547370cf6e41449003512"),
"highLevelCode": NumberLong(3),
"description": [
{"_id": ObjectId("528547370cf6e41449003521"),
"lang": "en",
"desc": "desc in English"},
{"_id ": ObjectId("528547370cf6e41449003522"),
"lang": "fr",
"desc": "desc en francais"}],
"budget": NumberLong(12345)
}

Basically I want to store nested descriptions, which could be of multiple languages in the Project document.

The code I wrote is:

import reactivemongo.bson._
import reactivemongo.bson.handlers.{BSONWriter, BSONReader}
import reactivemongo.bson.BSONLong
import reactivemongo.bson.BSONString

case class LocaleText(
id: Option[BSONObjectID],
lang: String,
textDesc: String
)

object LocaleText {
implicit object LocaleTextBSONReader extends BSONReader[LocaleText] {
def fromBSON(document: BSONDocument): LocaleText = {
val doc = document.toTraversable

  LocaleText(
    doc.getAs[BSONObjectID]("_id"),
    doc.getAs[BSONString]("lang").map(_.value).get,
    doc.getAs[BSONString]("textDesc").map(_.value).get
  )
}

}

implicit object LocaleTextBSONWriter extends BSONWriter[LocaleText] {
def toBSON(localText: LocaleText) = {
BSONDocument(
"_id" -> localText.id.getOrElse(BSONObjectID.generate),
"lang" -> BSONString(localText.lang),
"textDesc" -> BSONString(localText.textDesc)
)
}
}
}

case class Project(
id: Option[BSONObjectID],
description: List[LocaleText],
budget: Option[Long]
)

object Project {

implicit object ProjectReader extends BSONReader[Project]{
def fromBSON(doc: BSONDocument): Project = {
val document = doc.toTraversable

  Project(
    document.getAs[BSONObjectID]("_id"),
    document.getAs[BSONArray]("description").map { values =>
        values.values.toList.flatMap { case value =>
          value match {
            case v: LocaleText => Some(v.asInstanceOf[LocaleText])
            case _ => None
          }
        }
    }.getOrElse(List.empty),
    document.getAs[BSONLong]("budget").map(_.value)
  )
}

}

implicit object ProjectWriter extends BSONWriter[Project]{
def toBSON(project: Project): BSONDocument = {
BSONDocument(
"id" -> project.id.getOrElse(BSONObjectID.generate),
"description" -> BSONArray(project.description)
).append(Seq(
project.budget.map(b => "budget" -> BSONLong(b))
).flatten:*)
}
}
}

Scala doesn't like the line "description" -> BSONArray(project.description)

However, the following alternative, which is similar to your examples, works although I cannot use a List/Array to allow more than two languages:

case class LocaleText(
enDesc: String,
frDesc: String)

case class Project(
id: Option[BSONObjectID],
description: LocaleText)

object Project {
implicit object LocaleTextBSONReader extends BSONReader[LocaleText] {
def fromBSON(document: BSONDocument): LocaleText = {
val doc = document.toTraversable

  LocaleText(
    doc.getAs[BSONString]("enDesc").map(_.value).get,
    doc.getAs[BSONString]("frDesc").map(_.value).get
  )
}

}

implicit object LocaleTextBSONWriter extends BSONWriter[LocaleText] {
def toBSON(localText: LocaleText) = {
BSONDocument(
"enDesc" -> BSONString(localText.enDesc),
"frDesc" -> BSONString(localText.frDesc)
)
}
}

implicit object ProjectReader extends BSONReader[Project]{
def fromBSON(doc: BSONDocument): Project = {
val document = doc.toTraversable

Project(
document.getAsBSONObjectID,
document.getAsBSONString.map(_.value).get,
LocaleTextBSONReader.fromBSON(document.getAsBSONDocument.get)
}
}

implicit object ProjectWriter extends BSONWriter[Project]{
def toBSON(project: Project): BSONDocument = {
BSONDocument(
"_id" -> project.id.getOrElse(BSONObjectID.generate),
"iatiId" -> BSONString(project.iatiId),
"description" -> LocaleTextBSONWriter.toBSON(project.description)
}
}

I appreciate if you can shed some light on my problem. Thank you very much for your help.