problem mapping nested object in reactivemongo/Play

[Stefano Tondo]

Hi all,

I'm having an hard time figuring out how to properly map this model:

package models

import reactivemongo.bson.{

  BSONDateTime,

  BSONDocument,

  BSONObjectID

}

case class PixelDictModel(k: List[Int], v: Int)

object PixelDictModel {

  import play.api.libs.json._

  implicit object PixelDictWrites extends OWrites[PixelDictModel] {

    def writes(pixelDictModel: PixelDictModel): JsObject = Json.obj(

      "k" -> pixelDictModel.k,

      "v" -> pixelDictModel.v)

  }

  implicit object PixelDictModelReads extends Reads[PixelDictModel] {

    def reads(json: JsValue): JsResult[PixelDictModel] = json match {

      case obj: JsObject => try {

        val k = (obj \ "k").as[List[Int]]

        val v = (obj \ "v").as[Int]

        JsSuccess(PixelDictModel(k, v))

      } catch {

        case cause: Throwable => JsError(cause.getMessage)

      }

      case _ => JsError("expected.jsobject")

    }

  }

}

In my Play controller I'm parsing it correctly: val pixelDict = (request.body \ PixelDict).as[List[PixelDictModel]]

but when I pass it to my repository like that:

frameRepo.save(BSONDocument(

      Name -> name,

      Description -> description,

      Size -> BSONDocument("width" -> size.width, "height" -> size.height),

      Palette -> palette,

      Theater -> theater,

      Thumbnail -> thumbnail,

      PixelDict -> BSONArray(pixelDict) )).map(result => Created) 

  }

I'm getting this error:

• 
  Read from stdout: Compiling 3 Scala sources to /home/stondo/dev/scala/play-scala-mongo/target/scala-2.11/classes...
• Compiling 3 Scala sources to /home/stondo/dev/scala/play-scala-mongo/target/scala-2.11/classes...
• Read from stdout: /home/stondo/dev/scala/play-scala-mongo/app/controllers/FrameController.scala:56: overloaded method value apply with alternatives:
• Read from stdout: (stream: Stream[scala.util.Try[reactivemongo.bson.BSONValue]])reactivemongo.bson.BSONArray <and>
• Read from stdout: (elements: Traversable[reactivemongo.bson.BSONValue])reactivemongo.bson.BSONArray <and>
• Read from stdout: (elements: reactivemongo.bson.Producer[reactivemongo.bson.BSONValue]*)reactivemongo.bson.BSONArray
• Read from stdout: cannot be applied to (List[models.PixelDictModel])
• /home/stondo/dev/scala/play-scala-mongo/app/controllers/FrameController.scala:56: overloaded method value apply with alternatives: (stream: Stream[scala.util.Try[reactivemongo.bson.BSONValue]])reactivemongo.bson.BSONArray <and> (elements: Traversable[reactivemongo.bson.BSONValue])reactivemongo.bson.BSONArray <and> (elements: reactivemongo.bson.Producer[reactivemongo.bson.BSONValue]*)reactivemongo.bson.BSONArray cannot be applied to (List[models.PixelDictModel])
• Read from stdout: PixelDict -> BSONArray(newFrame.pixelDict) )).map(result => Created)
• PixelDict -> BSONArray(newFrame.pixelDict) )).map(result => Created)
• Read from stdout: ^
• ^
• Read from stdout: one error found
• one error found
• Read from stdout: (compile:compileIncremental) Compilation failed
• (compile:compileIncremental) Compilation failed
• Total time: 1 s, completed Sep 28, 2016 3:19:01 PM

 

Tried everything I could think of, but couldn't get it to work.

Any clues would be very much appreciated.

Thanks,

Stefano Tondo 

[Cédric Chantepie]

Hi,

As indicated in the error message, the BSONArray factory "cannot be applied to (List[models.PixelDictModel])" (and the indicated code is not the one causing this error).

It's recommanded to have a look at the API documentation.

Either you first convert the element of the list to BSONValues, to create a BSONArray from a Traversable[BSONValue], or call the vararg factory BSONArray(values: _*).

[Stefano Tondo]

Thanks for your answer and explanation Cédric.

I ended up changing the whole thing, using import play.api.libs.json.Reads._ instead, but I'll also try what u suggested.

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