Reads[T] validator error using ReactiveMongo

Question

I have a case class like this

case class Wish(_id: Option[String], title : String, text :String, cash: Int, created_at:    Option[DateTime], updated_at : Option[DateTime])

Also I have defined a implicit reads validator as below

implicit val wishFormat = Json.format[Wish]

I am trying to read a Mongodb document into my wish class and I get error like below

scala> val js = "{\"_id\":{\"$oid\":\"5259c384dd8251bb085adfb4\"},\"title\":\"Shrikar\",\"text\":\"test\",\"cash\":12.0,\"created_at\":1381614468235,\"updated_at\":1381614468235}"
js: String = {"_id":{"$oid":"5259c384dd8251bb085adfb4"},"title":"Shrikar","text":"test","cash":12.0,"created_at":1381614468235,"updated_at":1381614468235}

scala> val test = Json.parse(js)
test: play.api.libs.json.JsValue = {"_id":{"$oid":"5259c384dd8251bb085adfb4"},"title":"Shrikar","text":"test","cash":12.0,"created_at":1381614468235,"updated_at":1381614468235}

scala> test.validate[Wish]
res11: play.api.libs.json.JsResult[Wish] =   JsError(List((/_id,List(ValidationError(validate.error.expected.jsstring,WrappedArray())))))

Could you please help me resolve this issue?

score 1 · Answer 1 · answered Oct 13 '13 at 05:26

1

Your ID must be a BSONObjectID.

case class Wish(
  _id: Option[BSONObjectID],
  title: String,
  text: String,
  cash: Int,
  created_at: Option[DateTime],
  updated_at: Option[DateTime]
)

Then you must import the format from the Play-ReactiveMongo plugin:

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

answered Oct 13 '13 at 05:26

akkie

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I tried doing that but the form mapping fails if I take it as a BSONObjectId val wishForm : Form[Wish] = Form( mapping("_id"-> optional(BSONObjectID), "title" -> nonEmptyText ,"text" -> nonEmptyText,"cash" -> number(min = 0), "created_at" -> optional(of[DateTime]),"updated_at" -> optional(of[DateTime]))(Wish.apply)(Wish.unapply) ) – Shrikar Oct 13 '13 at 20:42
You can write "_id" -> ignored(BSONObjectID.generate) to generate a new one when the form will be submitted. Or you can use this approach: http://stackoverflow.com/questions/16898294/no-json-deserializer-found-for-type-optionreactivemongo-bson-bsonobjectid – akkie Oct 14 '13 at 06:12

score -1 · Accepted Answer · answered Oct 13 '13 at 04:52

-1

The reads format converts a play.api.libs.json.JsValue to an object. Reads is expecting a json value that looks like this:

import play.api.libs.json.{Json, JsValue}
val js: JsValue = Json.obj(
  "_id" -> "5259c384dd8251bb085adfb4",
  "title" -> "Shrikar",
  "text" -> "test",
  "cash" -> 12.0,
  "created_at" -> 1381614468235,
  "updated_at" -> 1381614468235
)

You should start by taking a look at the Playframework working with JSON documentation. If you are using a library such as ReactiveMongo, then mongodb queries should return a BSONDocument or JsValue. According to the Reactive Mongo docs:

With Play2-ReactiveMongo, you can use directly the embedded JSON library in Play >= 2.1. There is a specialized collection called JSONCollection that deals naturally with JSValue and JSObject instead of ReactiveMongo's BSONDocument.

If you can only receive mongodb query results as String, then you'll need to create a function to parse it into a JsValue.

I hope this helps!

answered Oct 13 '13 at 04:52

Alex

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Hi Alex I am using the the JSONCollection in latest reactive mongo plugin. But the views are operating on the Wish object hence I need to convert the Json Object into Wish so that I can pass it over to the view templates. The Json coast to coast document is really useful when you are dealing with Json response and seperated client side code for web or mobile . My use case is basically to convert the JSObject into Wish object. Is it because the _id is represented as a {"_id":{"$oid":"xyz"}} it not able to read it? – Shrikar Oct 13 '13 at 20:50
How can I map BSONObjectId to a form ? I see nonEmptyText, longNumber , optional values etc – Shrikar Oct 13 '13 at 20:52
@Shrikar, I think you need to do a custom validator using `(__ \ "_id" \ "$oid").formatNullable[BSONObjectID]` and change Wish._id to a change the id type to `Option[BSONObjectID]` – Alex Oct 14 '13 at 00:30

Reads[T] validator error using ReactiveMongo

2 Answers2