Scala/Play: parse JSON into Map instead of JsObject

Question

On Play Framework\'s homepage they claim that \"JSON is a first class citizen\". I have yet to see the proof of that.

In my project I\'m dealing with some pretty co

Answer 1

Would recommend reading up on pattern matching and recursive ADTs in general to better understand of why Play Json treats JSON as a "first class citizen".

That being said, many Java-first APIs (like Google Java libraries) expect JSON deserialized as Map[String, Object]. While you can very simply create your own function that recursively generates this object with pattern matching, the simplest solution would probably be to use the following existing pattern:

import com.google.gson.Gson
import java.util.{Map => JMap, LinkedHashMap}

val gson = new Gson()

def decode(encoded: String): JMap[String, Object] =   
   gson.fromJson(encoded, (new LinkedHashMap[String, Object]()).getClass)

The LinkedHashMap is used if you would like to maintain key ordering at the time of deserialization (a HashMap can be used if ordering doesn't matter). Full example here.