No Json serializer as JsObject found for type play.api.libs.json.JsObject

Question

I have the following code that works in a console app when referencing "org.reactivemongo" %% "play2-reactivemongo" % "0.10.5.0.akka23"

when I update the reference to "org.reactivemongo" % "play2-reactivemongo_2.11" % "0.11.0.play23-M3" I get:

No Json serializer as JsObject found for type play.api.libs.json.JsObject. Try to implement an implicit OWrites or OFormat for this type.

import org.joda.time.DateTime
import reactivemongo.bson.BSONObjectID
import play.modules.reactivemongo.json.BSONFormats._

case class GoogleToken
(
  id: Option[BSONObjectID],
  name: String,
  emailAddress: String,
  refreshToken: String,
  expires: DateTime
  )

object GoogleToken {

  import play.api.libs.json.Json

  // Generates Writes and Reads
  implicit val googleTokenFormat = Json.format[GoogleToken]
}

and then

val collection = db.collectionJSONCollection

val query = Json.obj()
val cursor = collection.find(query).
  cursor[GoogleToken](ReadPreference.nearest).
  collect[List]()

What am I doing wrong?

Nationalism

So I cannot fully recreate but comparing those two versions most of the dependencies remained the same but reactive mongo updated their internal libs. For what its worth that message your receiving is from ImplicitNotFound on OWrites. Its trying to take an instance of your type/class and create a JsObject. When you say console app - do you have app created or is this in the repl? I didn't see package names up above but perhaps they are just snippets. – Predesignate

It does make me wonder if something changed in the library where it wants a JsObject and the Format above on your case class is only creating reads/writes. – Predesignate

^^ above is wrong went through source and it only requires Writes – Predesignate

Thanks for taking a look. Apparently import play.modules.reactivemongo.json._ was required – Nationalism

Answer 1

The final release of ReactiveMongo 0.11 has been published ("org.reactivemongo" %% "play2-reactivemongo" % "0.11.0.play23").

As indicated on the updated documentation, for the default BSON/JSON conversions, it's recommended to have: import play.modules.reactivemongo.json._, ImplicitBSONHandlers._.

Straightway

import play.modules.reactivemongo.json._ did the trick! Thanks! – Nationalism

Note that the module version for Play 2.4 is 0.11.0.play24. – Straightway

with 0.11.2.play23, i've to do import play.modules.reactivemongo.json.ImplicitBSONHandlers._ – Ankara

I'm using 0.11.4.play24 and import import play.modules.reactivemongo.json._, ImplicitBSONHandlers._. The problem remains the same: "No Json serializer as JsObject found for type play.api.libs.json.JsObject". I couldn't even compile github.com/sgodbillon/reactivemongo-demo-app – Discounter

@pavel I stumbled over the same problem, after updating the dependencies of the reactivemongo-demo-app to Play 2.4.2 and ReactiveMongo 0.11.4.play24. I had to remove the import of ImplicitBSONHandlers._ to make it work. – Jujube

This may have been the solution for prior versions of reactivemongo but using "org.reactivemongo" % "play2-reactivemongo_2.12" % "0.12.7-play26", and above, if you're using the default json handlers, simply importing reactivemongo.play.json.JsObjectDocumentWriter will do the trick. – Illogicality

Answer 2

In my case, I was feeding ReactiveMongo (insert) with a JsValue instead than a JsObject. In order to fix it, behind adding import play.modules.reactivemongo.json._, I also had to change my implicit Writes in OWrites:

from

implicit val myWrites: Writes[A] = new Writes[A] {
  def writes(a: A) = Json.obj(...)

to

implicit val myWrites: OWrites[A] = new OWrites[A] {  <-- NOTE THE 'O' before 'Writes'
  def writes(a: A) = Json.obj(...)

Qualified

The OWrites is recommended when the specificity of writing an object is required. As soon as you write a JsObject, that's a good idea. – Straightway

If you use Play with ReactiveMongo, this is the solution you need. I changed all my Format to OFormat (you have to specify the type) and it worked. Example: case class Person(name: String, age: Int) object Person { implicit val jsonFormat: OFormat[Person] = Json.format[Person] } Notice the O in OFormat. – Bouilli

Answer 3

Mine worked out after adding: import play.modules.reactivemongo.json._ import play.modules.reactivemongo.json.collection._

Malarkey

Answer 4

try to add

import reactivemongo.play.json._

Palindrome

Answer 5

For me adding this import worked.

import play.modules.reactivemongo.json._

Ketone