Basic example of how a 'versioned' model might be implementable with ReactiveMongo

reactiveMongoVersionedModel.scala

// Expanding on basic case from 'Use Readers to deserialize documents automatically' http://reactivemongo.org/releases/0.10/documentation/tutorial/find-documents.html
case class Person(id: BSONObjectID, firstName: String, lastName: String, age: Int)

object Person {
  implicit object PersonReader extends BSONDocumentReader[Person] {
    def read(doc: BSONDocument): Person = {
      
      // Common fields
      val id = doc.getAs[BSONObjectID]("_id").get
      val version = doc.getAs[Int]("_version").get

      // Version matching
      val person = version match {
        case 1 => { // version 1
          val firstName = doc.getAs[String]("firstName").get
          val lastName = doc.getAs[String]("lastName").get
          val age = doc.getAs[Int]("age").get

          Person(id, firstName, lastName, age)
        }
        case _ => { // default/latest version
          val givenName = doc.getAs[String]("givenName").get
          val surname = doc.getAs[String]("surname").get
          val age = doc.getAs[Int]("age").get

          Person(id, givenName, surname, age)
        }
      }
      person // return
    }
  }
}