Scala Cookbook

15.4. Parsing JSON Data into an Array of Objects

Problem

You have a JSON string that represents an array of objects, and you need to deserialize it into objects you can use in your Scala application.

Solution

Use a combination of methods from the Lift-JSON library. The following example demonstrates how to deserialize the string jsonString into a series of EmailAccount objects, printing each object as it is deserialized:

import net.liftweb.json.DefaultFormats
import net.liftweb.json._

// a case class to match the JSON data
case class EmailAccount(
  accountName: String,
  url: String,
  username: String,
  password: String,
  minutesBetweenChecks: Int,
  usersOfInterest: List[String]
)

object ParseJsonArray extends App {

  implicit val formats = DefaultFormats

  // a JSON string that represents a list of EmailAccount instances
  val jsonString ="""
{
  "accounts": [
  { "emailAccount": {
    "accountName": "YMail",
    "username": "USERNAME",
    "password": "PASSWORD",
    "url": "imap.yahoo.com",
    "minutesBetweenChecks": 1,
    "usersOfInterest": ["barney", "betty", "wilma"]
  }},
  { "emailAccount": {
    "accountName": "Gmail",
    "username": "USER",
    "password": "PASS",
    "url": "imap.gmail.com",
    "minutesBetweenChecks": 1,
    "usersOfInterest": ["pebbles", "bam-bam"]
  }}
  ]
}
"""

  // json is a JValue instance
  val json = parse(jsonString)

  val elements = (json \\ "emailAccount").children
  for (acct <- elements) {
    val m = acct.extract[EmailAccount]
    println(s"Account: ${m.url}, ${m.username}, ${m.password}")
    println(" Users: " ...