Scala Edit Json Object and Write To a New Json Object - json

Question

So I have a json string in scala which looks something like this
"""
{
"input": {
"House" :{
"Tile" : "Ceramic"
"Kitchen" : {
"Sink" : "Stainless-Steel"
"Counter-Top" : "Granite"
}
}
}
}
"""
I'm using json4s to parse this and to put it into a Map and then I'm making it mutable so I can edit it, but I don't really know how to take it and modify it to make it a new json object.
import org.json4s.jackson.JsonMethods._
import org.json4s._
import org.json4s.native.Serialization._
import org.json4s.native.Serialization
import scala.collection.mutable
...
val reqJsonMap = parse(reqJson).extract[Map[String,Any]]
val reqJsonMutableMap= collection.mutable.Map[String,Any]()
reqJsonMutableMap ++=reqJsonMap
What I want to do is I want to edit it and make the json of Tile=Marble and change the key of Kitchen to Bathroom
I just don't know how to turn that object into this
"""
{
"input": {
"House" :{
"Tile" : "Marble"
"Bathroom" : {
"Sink" : "Stainless-Steel"
"Counter-Top" : "Granite"
}
}
}
}
"""

Answer 1

I think it is far better to work with case classes than with JSON. I think it is the most convenient to use a Json parsing library such as circe to parse your Json string into a case class, and then do whatever thing you need to do with it:
import io.circe._, io.circe.generic.auto._, io.circe.syntax._, io.circe.parser._
val myJsonString = """
{
"input": {
"house" :{
"tile" : "Ceramic",
"kitchen" : {
"sink" : "Stainless-Steel",
"counterTop" : "Granite"
}
}
}
}
"""
case class Data(input: Input)
case class Input(house: HouseInfo)
case class HouseInfo(tile: String, kitchen: KitchenInfo)
case class KitchenInfo(sink: String, counterTop: String)
val maybeDataJsonObject = parse(myJsonString)
val maybeData = maybeDataJsonObject match {
case Right(dataJsonObject) => dataJsonObject.as[Data]
case Left(failure) => println(failure)
}
maybeData match {
case Right(data) => println(data)
case Left(failure) => println(failure)
}
By the way, the format of your json is not good, because you have capitalized the initials of the field names, which should conventionally be lower cased. Also, you have written it as Counter-Top, instead of let’s say counterTop and the - character would be problematic in field names in Scala.
For applying the transformations you are looking for, you need to write new case classes with desired field names, then you can write a transformer function to transform the obtained Data object into the TransformedData one. Then you would be able to use circe to obtain a new Json string by coding the case class in Json, like in this:
val transformedJsonString = myTransformedData.asJson.toString