I am receiving a JSON from an external service and my goal is to parse it exactly as it is.
The main issue is this: a value can be nullable or it can be absent BUT null has different meaning of absent. So I want to catch this somehow.
For example this JSON:
{ "a": null, "b": 1 } is different from this one:
{ "b": 1 } Can you help me please?
UPDATE:
Sorry for the delay in the update. Anyway: you are right, I have a implicit custom reads in the middle and currently I use "a".readNullable[Double] and "a".write[Option[Double]] and case class is something like:
case class Example(a: Option[Double]) 1 Answer
Just laying out what @mfirry was talking about with a detailed example (play-json 2.6):
scala> import play.api.libs.json._ import play.api.libs.json._ scala> val json1 = Json.parse("""{"a": null, "b": 1}""") json1: play.api.libs.json.JsValue = {"a":null,"b":1} scala> val json2 = Json.parse("""{"b": 1}""") json2: play.api.libs.json.JsValue = {"b":1} scala> (json1 \ "a").isDefined res8: Boolean = true scala> (json1 \ "a") == JsDefined(JsNull) res3: Boolean = true scala> (json2 \ "a").isDefined res7: Boolean = false scala> (json2 \ "a") res5: play.api.libs.json.JsLookupResult = JsUndefined('a' is undefined on object: {"b":1}) 
