Play Framework and Scala Json, parsing for json containing JSArray and JSObject

Question

My sample json is either with a country object Json sample 1

  "@version": "1.0",
    "country": {
        "@country": "US",
        "day": {
            "@date": "2016-02-15",
            "@value": "1"
        }
    }

or with country array: Json sample 2

"@version": "1.0",
    "country": [{
        "@country": "US",
        "day": {
            "@date": "2016-02-15",
            "@value": "1"
        }
    }, {
        "@country": "UK",
        "day": {
            "@date": "2016-02-15",
            "@value": "5"
        }]
    }

To read the json

 implicit val dayJsonReads: Reads[DayJson] = (
      (JsPath \ "@date").read[DateTime](dateReads) and
        ((JsPath \ "@value").read[Int] orElse (JsPath \ "@value").read[String].map(_.toInt))
      )(DayJson.apply _)

    implicit val countryJsonReads: Reads[CountryJson] = (
      (JsPath \ "@country").read[String] and
        (JsPath \ "day").read[DayJson]
      )(CountryJson.apply _)

 implicit val newUserJsonReads: Reads[NewUserJson] = (
      (JsPath \ "@version").read[String] and
        (JsPath \ "country").readNullable[Seq[CountryJson]] 
      )(NewUserJsonParent.apply _)

The above code reads sample json 2 however fails for sample json 1. Is it possible to use readNullable to read either JS Value or JS Object or can we convert it from JS Value to JS Object. Thank you.

Tomer · Accepted Answer · 2016-02-17 15:45:39Z

4

You can do something like this:

object NewUserJson{
implicit val newUserJsonReads: Reads[NewUserJson] = (
  (JsPath \ "@version").read[String] and
    (JsPath \ "country").read[JsValue].map{
      case arr: JsArray => arr.as[Seq[CountryJson]]
      case obj: JsObject => Seq(obj.as[CountryJson])
    }
  )(NewUserJson.apply _)
}

This should work for this case class:

case class NewUserJson(`@version`: String, country: Seq[CountryJson])

But I don't like it, can't you just use the same structure, and when you have only one country just send a list that hold only one country, instead of object?

edited Feb 17, 2016 at 15:45

answered Feb 16, 2016 at 8:45

Tomer

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6 Comments

binshi Over a year ago

Thank you for your reply. Yes, I would like to convert the single object to a list. Can I write it like this? object NewUserJson{ implicit val newUserJsonReads: Reads[NewUserJson] = ( (JsPath \ "@version").read[String] and (JsPath \ "country").read[JsValue].map{ case arr: JsArray => arr.as[Seq[CountryJson]] case obj: JsObject => obj.as[Seq[CountryJson]] } )(NewUserJson.apply _) }

binshi Over a year ago

For the above, I keep getting "Application does not take parameters error"

Tomer Over a year ago

My answer did not work for you? you cannot read the object as Seq while it's a single object.

binshi Over a year ago

It did not work. Should I change the case class type too?

Tomer Over a year ago

I updated the answer, the case class should be : case class NewUserJson(@version: String, country: Seq[CountryJson]) If it doesn't work for you I can share the full example, and the test that passed for both jsons. Tell me if it worked for you or not.

|

binshi · Accepted Answer · 2016-02-18 03:50:19Z

1

Working on Tomer's solution, below is a working sample. It would be nice if I can make it more compact.

Case class

case class NewUserJson(version: String, country: Option[Seq[CountryJson]])

Json parsing object

 object NewUserJson{
    implicit val newUserJsonReads: Reads[NewUserJson] = (
      (JsPath \ "@version").read[String] and
        (JsPath \ "country").readNullable[JsValue].map {
          arr => {
            if (!arr.isEmpty){
              arr.get match {
                case arr: JsArray => Option(arr.as[Seq[CountryJson]])
                case arr: JsObject => Option(Seq(arr.as[CountryJson]))
              }
            }else {
              None
            }
          }
        }
      )(NewUserJson.apply _)
    }

answered Feb 18, 2016 at 3:50

binshi

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1 Comment

andrey.ladniy Over a year ago

Tomer wrote write solution. If you want use nullable, you can modify his code to "readNullable[JsValue].map{_.map{case arr: JsArray => ...}}

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