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mongodbscalacasbahsalat

Salat MongoDB DAO findOneById how to

I have recently started using Scala, Akka and the Salat serialization library for MongoDB. Now I am trying to set up a SalatDAO for objects that look like this:

import com.novus.salat.annotations._

case class MyObject(@Key("_id) compId: MyCompositeId, value: String)
case class MyCompositeId(x: String, y: String)

and I created a DAO like the following:

import com.novus.salat.global._
import com.novus.salat.dao._
import com.mongodb.casbah.{MongoURI, MongoConnection}
import com.mongodb.casbah.commons.MongoDBObject

class MyObjectDAO(uri: String, db: String, coll: String) 
  extends SalatDAO[MyObject, MyCompositeId](MongoConnection(MongoURI(uri))(db)(coll))

Finally I wrote a simple unit test:

val dao = new MyObjectDAO(...)

val id = new MyCompositeId("some","key)

// works fine
dao.findOne(MongoDBObject("_id.x" -> id.x, "_id.y" -> id.y))
// does NOT work
dao.findOneById(id)

the first call will return Some(_) while the second one will return None.

Now I looked at the source code for findOneById to try and understand why it's not working:

/** @param id identifier
 *  @return (Option[ObjectType]) Some() of the object found, 
 *          or <code>None</code> if no such object exists
 */
def findOneById(id: ID) =
  collection.findOneByID(id.asInstanceOf[AnyRef]).map(_grater.asObject(_))

And it smells a lot like a bug to me: the method is passing to collection.findOneByID() an object of type MyCompositeId which the Casbah driver doesn't understand. I believe Salat is supposed to serialize this object to a MongoDBObject before passing it.

Am I correct? Is this a bug? Or is there something I am missing?

Thanks

Solution

  • Discussion on this Salat project ticket: https://github.com/novus/salat/issues/110