Base document with multiple instances

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stephanos

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Mar 1, 2013, 9:08:21 AM3/1/13
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I'm stuck on this all day already, I hope someone has an idea how to solve this.

Basically I have a base document that has a few instances (db.doc0, db.doc1 etc.):

import com.foursquare.rogue.LiftRogue._
import net.liftweb.mongodb.record.{MongoRecord, MongoMetaRecord}
 
// ==== BASE
 
trait BaseDoc[T <: MongoRecord[T]]
  extends MongoRecord[T] {
 
  self: T =>
 
  object id
}
 
trait BaseMeta[T <: BaseDoc[T]]
  extends MongoMetaRecord[T] {
 
  self: T =>
}
 
// ==== DOC #1
 
class BaseDoc1 extends BaseDoc[BaseDoc1] {
  def meta = BaseMeta1
}
object BaseMeta1 extends BaseDoc1 with BaseMeta[BaseDoc1]
 
// ==== DOC #2
 
class BaseDoc2 extends BaseDoc[BaseDoc2] {
  def meta = BaseMeta2
}
object BaseMeta2 extends BaseDoc2 with BaseMeta[BaseDoc2]
 
// ==== QUERY
 
case class Mod(num: Int) {
  def doc: BaseMeta[_] with BaseDoc[_] = // WRONG
    num % 2 match {
      case 0 => BaseMeta1
      case _ => BaseMeta2
    }
}
 
object Main {
 
  val doc = Mod(0).doc
  doc.where(_._id eqs 42)
}


The error I'm getting is

error: value where is not a member of BaseMeta[_] with BaseDoc[_]
doc.where(_._id eqs 42)

Obviously the implicit conversation is not triggered because the return type of doc is wrong.

But how do I fix it?


Regards
Stephan

stephanos

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Mar 2, 2013, 3:49:39 AM3/2/13
to rogue...@googlegroups.com
I think I got it:

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 with BaseDoc =
    num % 2 match {
      case 0 => BaseMeta1
      case _ => BaseMeta2
    }
}
 
object Main extends App {
  import com.foursquare.rogue.LiftRogue._
 
  val doc = Mod(0).meta
  doc.where(_.int eqs 42)
}

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