record.scala

import net.liftweb.mongodb.record.field.ObjectIdField
import net.liftweb.mongodb.record.{MongoMetaRecord, MongoRecord}
import net.liftweb.record.field.IntField

// ==== BASE

trait BaseDoc
  extends MongoRecord[BaseDoc] {

  def id = _id.value

  object _id extends ObjectIdField(this)
  object int extends IntField(this)
}

trait BaseMeta
  extends MongoMetaRecord[BaseDoc] {

  self: BaseDoc =>
}

// ==== DOC #1

class BaseDoc1 extends BaseDoc {
  def meta = BaseMeta1
}

object BaseMeta1 extends BaseDoc1 with BaseMeta

// ==== DOC #2

class BaseDoc2 extends BaseDoc {
  def meta = BaseMeta2
}

object BaseMeta2 extends BaseDoc2 with BaseMeta

// ==== QUERY

case class Mod(num: Int) {

  def meta: BaseMeta =
    num % 2 match {
      case 0 => BaseMeta1
      case _ => BaseMeta2
    }
}

object Main extends App {
  val doc = Mod(0).meta.createRecord.int(5)
}