Scala: Parse JSON directly into a case class

Question

Given a string of JSON, and a case class that corresponds to it, what\'s a simple way to parse the JSON into the case class? There are many libraries available, but it seem

Answer 1

I second the JSON conversion in the Play Framework.

Also take a look at Jackson which is mature. Note you will need to use Jackson Scala Module : https://github.com/FasterXML/jackson-module-scala.

A decent article providing an intro - then some code to add implicit conversions : https://coderwall.com/p/o--apg/easy-json-un-marshalling-in-scala-with-jackson

Answer 2

For anyone bumping into this for the first time, circe is also a good option

val customerJson = s"""{"id" : "1", "name" : "John Doe"}"""
case class Customer(id: String, name: String)
val customer = decode[Customer](customerJson)

Answer 3

I've used https://github.com/json4s/json4s , only gripe so far is https://github.com/json4s/json4s/issues/137

import org.json4s._
import org.json4s.native.JsonMethods._

implicit val formats = DefaultFormats

case class ParsedPage(crawlDate: String, domain:String, url:String, text: String)

val js = """ {
"crawlDate": "20150226",
"domain": "0x20.be",
"url": "http://0x20.be/smw/index.php?title=99_Bottles_of_Beer&oldid=6214",
"text": "99 Bottles of Beer From Whitespace (Hackerspace Gent) Revision as of 14:43, 8 August 2012 by Hans ( Talk | contribs ) 99 Bottles of Beer Where: Loading map... Just me, with 99 bottles of beer and some friends. Subpages"
}"""


parse(js).extract[ParsedPage]

Answer 4

Spray Json is pretty light weight and does exactly what you need. It's a toolkit instead of a full on framework and you can just import the Spray-json project instead of the entire project.

https://github.com/spray/spray-json

The examples can get you set up very quickly. Most of the time your code to translate to/from JSON ends up being one liners, but you have the ability to explicitly handle it in case you have some weird requirements.

Answer 5

Use net.liftweb

import net.liftweb.json._
case class Detail(username:String, password:String)
implicit val formats = DefaultFormats
val input = parse(jsonString).extract[Detail]
println(input.username)

Make sure the Scala version matches the lift-json jar. For ex. for Scala 2.10 use lift-json_2.10.

Answer 6

Use spray-json as it is small.

import spray.json._
import DefaultJsonProtocol._


val json = """{"one" : "1", "two" : "2", "three" : "3"}""".parseJson

case class Numbers(one: String, two: String, three: String)

object MyJsonProtocol extends DefaultJsonProtocol {
  implicit val numbersFormat = jsonFormat3(Numbers)

}

import MyJsonProtocol._

val converted = json.convertTo[Numbers]

Download spray-json into sbt using this build.sbt:

lazy val root = (project in file(".")). settings( name := "jsonExample", libraryDependencies += "io.spray" %% "spray-json" % "1.3.2" )