Parse Numeric OR String value from Json response - Scala - Play

Question

I understand this shouldn't happen, but a 3rd party API is returning JSON response, with the exact same field EITHER as Double/Float or as a String. After much internal debate of "why we live in a world like this", I'm struggling to find a way to parse such a response:

implicit val inconsistentReads: Reads[InconsistentItem] = (
  (JsPath \ "field").readNullable[String] ... 
)(InconsistentItem.apply _)

When this runs, I'm getting "play.api.libs.json.JsResultException: JsResultException" when the field sometimes is returned as a numeric value.

Would it be possible to read it in as String, regardless of if it was numeric or String in the Json response?

This is for Scala in Play Framework. Much thanks!

Jamie · Accepted Answer · 2016-12-12 20:21:31Z

4

Try something like this. Since you don't define what InconsistentItem is, I use Either.

val inconsistentReads = Reads[Either[String, BigDecimal]] {
     case JsNumber(a) => JsSuccess(Right(a))
     case JsString(a) => JsSuccess(Left(a))
     case _ => JsError("Type not supported")
     }

Examples:

Json.parse("\"hi\"").validate[Either[String, BigDecimal]](inconsistentReads)
# JsSuccess(Left("hi"))
Json.parse("1").validate[Either[String, BigDecimal]](inconsistentReads)
# JsSuccess(Right(1))

answered Dec 12, 2016 at 20:21

Jamie

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1 Comment

ulric260 Over a year ago

A more generic defintion of Reads[Either]: gist.github.com/graingert/…

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