Read json key value but ignore object

Question

I have the below json

"atrr": {
     "data": {
          "id": "asfasfsaf",
          "name": "cal",
          "type": "state"
          "ref": [
            "xyz",
            "uhz",
            "arz"
          ]
        }
}

I am reading this as below but not getting value k,v

def getData: Map[String, String] = (atrr \ "data").asOpt[Map[String, String]].getOrElse(Map[String, String]())

without ref it works fine.how do I ignore ref[] from json in code that is an object

Answer 1

You can use a custom Reads[Map[String, String]], passed to the .as or .asOpt method. My approach is to use Reads.optionNoError[String] to handle the values inside the main atrr object, so that any non-string field which would have caused an error will instead be treated as a None.

// explicitly construct something that'd normally be constructed implicitly
val customReads: Reads[Map[String, Option[String]] = 
  Reads.map(Reads.optionNoError[String])

// pass the custom reads explicitly with parens,
// instead of passing the expect type in square brackets
(atrr \ "data").asOpt(customReads)

This results in

Some(
  Map(
    id -> Some(asfasfsaf), 
    name -> Some(cal), 
    type -> Some(state), 
    ref -> None
  )
)

which you can transform how you see fit, for example by doing

.map(_.collect { case (k, Some(v)) => k -> v })