Fastest way to convert nested String to JSON [duplicate] - json

Question

Is there a straight forward way to format a JSON string in scala?
I have a JSON String like this:
val json = {"foo": {"bar": {"baz": T}}}
Can I use a function f such that:
f(json) = {
"foo":
{"bar":
{"baz": T}
}
}
I know the formatting I have done in my answer is no perfect, but you get the point. And yes, can it be done without using Play Framework?

Answer 1

In case you are using Play Framework you could use Json.prettyPrint method to format JsValue:
import play.api.libs.json.Json
val str = """{"foo": {"bar": {"baz": "T"}}}"""
val jsValue = Json parse str
// JsValue = {"foo":{"bar":{"baz":"T"}}}
Json prettyPrint jsValue
// String =
// {
// "foo" : {
// "bar" : {
// "baz" : "T"
// }
// }
// }
In case you are using scala.util.parsing.json you have to create such method by yourself. For instance:
def format(t: Any, i: Int = 0): String = t match {
case o: JSONObject =>
o.obj.map{ case (k, v) =>
" "*(i+1) + JSONFormat.defaultFormatter(k) + ": " + format(v, i+1)
}.mkString("{\n", ",\n", "\n" + " "*i + "}")
case a: JSONArray =>
a.list.map{
e => " "*(i+1) + format(e, i+1)
}.mkString("[\n", ",\n", "\n" + " "*i + "]")
case _ => JSONFormat defaultFormatter t
}
val jsn = JSON.parseRaw("""{"foo": {"bar": {"baz": "T"}, "arr": [1, 2, "x"]}, "foo2": "a"}""").get
// JSONType = {"foo" : {"bar" : {"baz" : "T"}, "arr" : [1.0, 2.0, "x"]}, "foo2" : "a"}
format(jsn)
// String =
// {
// "foo": {
// "bar": {
// "baz": "T"
// },
// "arr": [
// 1.0,
// 2.0,
// "x"
// ]
// },
// "foo2": "a"
// }
Note that this is not an efficient implementation.

Answer 2

I thought I read somewhere that Typesafe was considering separating their JSON processing out of Play, so look into that to apply #senia's solution first.
Otherwise, look at Jackson--or more precisely, the Scala wrapper for Jackson:
val mapper = new ObjectMapper()
mapper.registerModule(DefaultScalaModule)
val writer = mapper.writerWithDefaultPrettyPrinter
val json = writer.writeValueAsString(Object value)
I've also heard that the kids are really into Scala Pickling, which apparently has pretty printing as well.