How do I turn a Scala case class into a mongo Document - mongodb

Question

I'd like to build a generic method for transforming Scala Case Classes to Mongo Documents.
A promising Document constructor is
fromSeq(ts: Seq[(String, BsonValue)]): Document
I can turn a case class into a Map[String -> Any], but then I've lost the type information I need to use the implicit conversions to BsonValues. Maybe TypeTags can help with this?
Here's what I've tried:
import org.mongodb.scala.bson.BsonTransformer
import org.mongodb.scala.bson.collection.immutable.Document
import org.mongodb.scala.bson.BsonValue
case class Person(age: Int, name: String)
//transform scala values into BsonValues
def transform[T](v: T)(implicit transformer: BsonTransformer[T]): BsonValue = transformer(v)
// turn any case class into a Map[String, Any]
def caseClassToMap(cc: Product) = {
val values = cc.productIterator
cc.getClass.getDeclaredFields.map( _.getName -> values.next).toMap
}
// transform a Person into a Document
def personToDocument(person: Person): Document = {
val map = caseClassToMap(person)
val bsonValues = map.toSeq.map { case (key, value) =>
(key, transform(value))
}
Document.fromSeq(bsonValues)
}
<console>:24: error: No bson implicit transformer found for type Any. Implement or import an implicit BsonTransformer for this type.
(key, transform(value))

Answer 1

def personToDocument(person: Person): Document = {
Document("age" -> person.age, "name" -> person.name)
}

Answer 2

Below code works without manual conversion of an object.
import reactivemongo.api.bson.{BSON, BSONDocument, Macros}
case class Person(name:String = "SomeName", age:Int = 20)
implicit val personHandler = Macros.handler[Person]
val bsonPerson = BSON.writeDocument[Person](Person())
println(s"${BSONDocument.pretty(bsonPerson.getOrElse(BSONDocument.empty))}")

Answer 3

You can use Salat https://github.com/salat/salat. A nice example can be found here - https://gist.github.com/bhameyie/8276017. This is the piece of code that will help you -
import salat._
val dBObject = grater[Artist].asDBObject(artist)
artistsCollection.save(dBObject, WriteConcern.Safe)

Answer 4

I was able to serialize a case class to a BsonDocument using the org.bson.BsonDocumentWriter. The below code runs using scala 2.12 and mongo-scala-driver_2.12 version 2.6.0
My quest for this solution was aided by this answer (where they are trying to serialize in the opposite direction): Serialize to object using scala mongo driver?
import org.mongodb.scala.bson.codecs.Macros
import org.mongodb.scala.bson.codecs.DEFAULT_CODEC_REGISTRY
import org.bson.codecs.configuration.CodecRegistries.{fromRegistries, fromProviders}
import org.bson.codecs.EncoderContext
import org.bson.BsonDocumentWriter
import org.mongodb.scala.bson.BsonDocument
import org.bson.codecs.configuration.CodecRegistry
import org.bson.codecs.Codec
case class Animal(name : String, species: String, genus: String, weight: Int)
object TempApp {
def main(args: Array[String]) {
val jaguar = Animal("Jenny", "Jaguar", "Panthera", 190)
val codecProvider = Macros.createCodecProvider[Animal]()
val codecRegistry: CodecRegistry = fromRegistries(fromProviders(codecProvider), DEFAULT_CODEC_REGISTRY)
val codec = Macros.createCodec[Animal](codecRegistry)
val encoderContext = EncoderContext.builder.isEncodingCollectibleDocument(true).build()
var doc = BsonDocument()
val writr = new BsonDocumentWriter(doc) // need to call new since Java lib w/o companion object
codec.encode(writr, jaguar, encoderContext)
print(doc)
}
};