Handling optional values in BSONDocument

Question

I am having difficulty with the way optional values are handled by BSONDocuments in an application. I started with the "eventual" template from Typesafe activator (play/reactivemongo/angular). I created a case class representing an object to go into Mongo, and some of the values are Options:

case class Item(
   id: Option[BSONObjectID],
   manufacturer: String,
   minPrice: Option[Double],
   maxPrice: Option[Double])

The problem I am having is that the optional values are getting written to Mongo as arrays. For example purposes, use "Acme" as the manufacturer, 88 as the minPrice and None as the maxPrice. Printjson in Mongo shows that this looks like

{
    _id = BSONObjectID("...")
    manufacturer: "Acme",
    maxPrice: [ ],
    minPrice: [
       88
    ]
}

I can't read back the array values from Mongo as a simple option value when creating an object from the database values.

Item(
   ....
   bsondoc.getAs[Double]("minPrice"),
   ....
)

That getAs() statement always returns None, although bsondoc.get("minPrice") does have the value Some(BSONDocument())

I printed the data being sent to Mongo for an update, and sure enough, the code that creates the modifier statement is sending the optional value as an array, either empty, or containing one element.

val modifier = BSONDocument(
    "$set" -> BSONDocument(
      "manufacturer" -> manufacturer,
      "minPrice" -> minPrice,
      "maxPrice" -> maxPrice
    ))

This pretty prints as

{
  $set: {
    manufacturer: BSONString(Acme),
    maxPrice: [

    ],
    minPrice: [
      0: BSONDouble(88.0)
    ]
  }
}

Is there are right way to be handling these optional values?

To add to the mystery, I put the same modifier-creating code in a worksheet (in Eclipse), and I get a different result:

{
   $set: {
      manufacturer = BSONString(Acme),
      minPrice = BSONInteger(88)
   }
}

The optional values do not have an array. If they are none, they don't appear. This would work fine for my application, but something is changing the BSONDocument handling of optional elements inside the application. Does anyone know why?

I did enough tracing in debug to figure out that after creating a Tuple2 containing the name and the value, an anonymous function calls the BSON Double handler and then calls collectionToBSONArrayCollectionWriter. I can't see the code in that function, so it is hard to tell what is going on. — Willard, Apr 15 '14 at 04:09
@Willard Curious if you ever found a solution to this, as I am experiencing the same problem? — shuttj, Jan 26 '17 at 18:29

score 1 · Answer 1 · answered Jan 27 '17 at 16:28

For future reference I discovered that this was happening because I had the following implicit import:

import reactivemongo.bson.Producer.nameValue2Producer

When I removed that import, it worked as I expected

Using reactive mongo version 0.10.5.0.akka23.

Handling optional values in BSONDocument

1 Answers1