How to force number field to be parsed as Double even if it is Int using play.api.libs.json library in Scala

Question

Bellow is the snippet from Scala REPL, how do I make a json like {"a":2.0}?

scala> val f = 2.0
f: Double = 2.0

scala> f
res2: Double = 2.0

scala> val x = play.api.libs.json.Json.obj("a" -> f)
x: play.api.libs.json.JsObject = {"a":2}

Answer 1

In Play JSON library you've got following JSON types:

• JsString
• JsNumber
• JsBoolean
• JsObject
• JsArray
• JsNull

Which corresponds to JSON types. It wraps your value into type JsNumber. If you would save the same way val f = 2.1 you would receive x: play.api.libs.json.JsObject = {"a":2.1}. JsNumbers behaves like JavaScript numbers, so you don't have to worry about missing zeros at the end. In JavaScript 2 and 2.0 are the same numbers.