JsonArray in Scala

Question

currently this is what I could get

{
    "friends": [438737,
        12345,
        32153,
        53243
    ]
}

achievable by doing creating a case class

case class FriendsModel(uid: Option[String])
object FriendsModel {
  implicit val paramsWrite = Json.writes[FriendsModel]
  implicit val paramsRead = Json.reads[FriendsModel]
}

and basically adding the friendsModel to a List[FriendsModel] called friendList

and I could just Ok(Json.toJson(friendList))

Is there a way to insert variable as "friends" so my Json return would look like this:

{
    "123654": [438737,
        12345,
        32153,
        53243
    ]
}

where 123654 is my userid.

According to your code, Json.toJson(friends) should return play.api.libs.json.JsValue = [{"uid":"12"},{"uid":"13"},{"uid":"14"}], can you explain how are you getting the output you mentioned — Adi
– Adi, Commented Jun 23, 2016 at 12:18
Sorry, actually it was case class FriendsModel(uid: Option[MyCustomModel]) — kenlz
– kenlz, Commented Jun 24, 2016 at 2:45

vdebergue · Accepted Answer · 2016-06-23 14:04:32Z

6

I would create a case class to encapsulate the data:

case class User(uid: String, friends: Seq[FriendsModel])

and create a Json writer for this type:

object User {
  implicit val writer: Writes[User] = Writes { user =>
    Json.obj(
      user.uid -> user.friends
    )
  }
}

This will get you { "123654": [438737,...] }

answered Jun 23, 2016 at 14:04

vdebergue

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2 Comments

Daniel Over a year ago

Every time you want to get rid of field names you will need to implement a custom writer, as stated in this answer

kenlz Over a year ago

Thanks! this confirmed the result!

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