No Json deserializer found for type Option[reactivemongo.bson.BSONObjectID]

问题

I'm getting a:

No Json deserializer found for type Option[reactivemongo.bson.BSONObjectID]. Try to implement an implicit Reads or Format for this type.

When trying to deserialise my review object.

Review:

case class Review(override var id: Option[BSONObjectID] = None,
                  override var createdAt: Option[DateTime] = None,
                  override var updatedAt: Option[DateTime] = None,
                  grade: Int,
                  text: String,
                  originIPAddress: Option[String],
                  status: ReviewStatus,
                  origin: ReviewOrigin,
                  rId: Option[Long],
                  userId: Option[Long]
                  ) extends TemporalModel

object Review {

  import mongo_models.enums.EnumFormat._
  implicit val reviewStatusReads = enumReads(ReviewStatus)
  implicit val reviewOriginReads = enumReads(ReviewOrigin)

  implicit val reviewReads: Reads[Review] = (
    (__ \ "id").read[Option[BSONObjectID]] and
      (__ \ "createdAt").read[Option[DateTime]] and
      (__ \ "updatedAt").read[Option[DateTime]] and
      (__ \ "grade").read[Int] and
      (__ \ "text").read[String] and
      (__ \ "originIPAddress").read[Option[String]] and
      (__ \ "status").read[ReviewStatus] and
      (__ \ "origin").read[ReviewOrigin] and
      (__ \ "rId").read[Option[Long]] and
      (__ \ "userId").read[Option[Long]]
    )(Review.apply _)

  implicit val reviewWrites: Writes[Review] = (
    (__ \ "id").write[Option[BSONObjectID]] and
      (__ \ "createdAt").write[Option[DateTime]] and
      (__ \ "updatedAt").write[Option[DateTime]] and
      (__ \ "grade").write[Int] and
      (__ \ "text").write[String] and
      (__ \ "originIPAddress").write[Option[String]] and
      (__ \ "status").write[ReviewStatus] and
      (__ \ "origin").write[ReviewOrigin] and
      (__ \ "rId").write[Option[Long]] and
      (__ \ "userId").write[Option[Long]]
    )(unlift(Review.unapply))



  val form = Form(
    mapping(
      "id" -> optional(of[String] verifying pattern(
        """[a-fA-F0-9]{24}""".r,
        "constraint.objectId",
        "error.objectId")),
      "creationDate" -> optional(of[Long]),
      "updateDate" -> optional(of[Long]),
       "grade" -> number,
       "text" -> text(minLength = 30, maxLength = 5000),
      "originIPAddress" -> optional(of[String]),
      "status" -> text,
      "origin" -> text,
      "rId" -> optional(of[Long]),
      "userId" -> optional(of[Long])
    ) {
      (id, createdAt, updatedAt, grade, text, originIPAddress, status, origin, rId, userId) =>
        Review(
          id.map(new BSONObjectID(_)),
          createdAt.map(new DateTime(_)),
          updatedAt.map(new DateTime(_)),
          grade,
          text,
          originIPAddress,
          ReviewStatus.withName(status),
          ReviewOrigin.withName(origin),
          rId,
          userId
        )
    } {
      review => {
        Some(
          (review.id.map(_.stringify)),
          review.createdAt.map(_.getMillis),
          review.updatedAt.map(_.getMillis),
          review.grade,
          review.text,
          review.originIPAddress,
          review.status.toString,
          review.origin.toString,
          review.rId,
          review.userId
        )
      }
    }
  )
}

回答1:

Strange! My Intellij IDEA 12 didn't recognise the import and when I optimised the imports

import play.modules.reactivemongo.json.BSONFormats._

was removed which created the error.

One could also create a custom Format object to translate the BSONObjectID to json.

implicit object BSONObjectIDFormat extends Format[BSONObjectID] {
    def writes(objectId: BSONObjectID): JsValue = JsString(objectId.toString())
    def reads(json: JsValue): JsResult[BSONObjectID] = json match {
      case JsString(x) => {
        val maybeOID: Try[BSONObjectID] = BSONObjectID.parse(x)
        if(maybeOID.isSuccess) JsSuccess(maybeOID.get) else {
          JsError("Expected BSONObjectID as JsString")
        }
      }
      case _ => JsError("Expected BSONObjectID as JsString")
    }
  }

But the import is enough in this case.

回答2:

Use this as per documentation: import reactivemongo.play.json._

来源：https://stackoverflow.com/questions/16898294/no-json-deserializer-found-for-type-optionreactivemongo-bson-bsonobjectid