Play Json case class mapper with custom converter function

Question

I have a json which looks like this.

{
"key1": "val1",
"key2": "val2",
//other stuff
"key5": {
  "nkey1": [
    "nval1",
    "nval2"
  ],
  "nkey2": 90,
  "nkey3": 100
},
"page": 1,
"rows": 30,
"result_count": 3,
"parser_result": null,
"ip_address": "10.0.0.1",
"search_date": "20151013 05:12:05",
"key6": [
  //more key values
]
}

I need an object mapper for the same using scala case classes using the play framework. I can write conversions for simple classes. However I have some custom functionality which is given in the getMap class which takes an instance of jObject within JsPath \ "key5" as given in the code below. How do I go about implementing this as my method would not be able to achieve this it seems.

implicit val myReads: Reads[MyCustomObject] = (
  (JsPath \ "key1").read[String] and
    (JsPath).read[CustomObject] and
    (JsPath \ "key3").read[String] and
    (JsPath \ "key4").readNullable[String] and
    (JsPath \ "key5").read(/*How do I call getMap here*/) and
    (JsPath \ "key6").read[Seq[CustomObject2]]
  )(SearchQuery.apply _)

def getMap(jsObject: JsObject):Map[String, List[JsValue]] ={
  val r = Map[String, List[JsValue]]() ++ jsObject.fields.map(keyValues => {
    keyValues._2 match {
      case JsArray(arr) => keyValues._1 -> arr.toList
      case v: JsValue => keyValues._1 -> List(v)
      case _ => keyValues._1 -> List()
    }
  })
  r
}

Answer 1

I used the following snippet to resolve my problem. Basically this is just another constructor that could be modified using regular scala syntax.

implicit val myReads: Reads[MyCustomObject] = (
  (JsPath \ "key1").read[String] and
  (JsPath).read[CustomObject] and
  (JsPath \ "key3").read[String] and
  (JsPath \ "key4").readNullable[String] and
  (JsPath \ "key5").read(JsValue) and
  (JsPath \ "key6").read[Seq[CustomObject2]]
)(key1: String, custom: CustomObject, key3: String, key4: Option[String,
  key5: JsValue, key6: Seq[CustomObject2){
  SearchQuery.apply(key1, custom, key3, key4, transformToMap(key5), key6) // Where transformToMap is a custom function that I have defined.
}