Json4s + salat sample

gistfile1.scala

import java.util.Date

// define some classes
case class Child (name: String, birthdate: Date)
case class Spouse (name: String, birthdate: Date)

case class Address (address1: String,
  address2: String,
  city: String,
  state: String,
  zip: String)

case class UserSettings (
  wantsGeneralNotifications: Boolean,
  wantsUpdates: Boolean)

case class User (username: String,
  email: String,
  addresses: List[Address],
  spouses: List[Spouse],
  children: List[Child],
  settings: UserSettings)


import org.json4s._
import org.json4s.JsonDSL._
import org.json4s.jackson.JsonMethods._
import org.json4s.native.Serialization.{read, write}

// deserialize json into object with default formats
implicit val formats = DefaultFormats

// turn json into an object
val jsonString = """
{
  "username":"johnny",
  "email":"[email protected]",
  "addresses":[
    {
      "address1":"195 E. 4th Ave",
      "address2":"2nd floor",
      "city":"San Mateo",
      "state":"CA",
      "zip":"94401"
    }
  ],
  "settings":{
    "wantsGeneralNotifications":true,
    "wantsUpdates":true
  }
}
"""

val json = parse(jsonString)
val userObject = json.extract[User]

// serialize an object into JSON
val user = User("fehguy",
  "[email protected]", 
  List(
    Address("195 E. 4th Ave", "2nd floor", "San Mateo", "CA", "94401")
  ),
  List.empty,
  List.empty,
  UserSettings(true, true)
)

implicit val formats = DefaultFormats

// turn an object into json
write(user)

// a custom serializer to handle missing fields on the input
class AddressSerializer extends CustomSerializer[Address](formats => ({
  case json =>
    implicit val fmts: Formats = formats
    Address(
      address1 = (json \ "address1"),                     // required!
      address2 = (json \ "address2").extractOrElse(""),   // handle empty values
      city = (json \ "city").extractOrElse(""),
      state = (json \ "state").extractOrElse(""),
      zip = (json \ "zip").extractOrElse("")
    )
}, {
  case x: Address =>
    implicit val fmts = formats
    ("address1" -> x.address1) ~
    ("address2" -> x.address2) ~
    ("city" -> x.city) ~
    ("state" -> x.state) ~
    ("zip" -> x.zip)
}))

implicit val formats = DefaultFormats + new AddressSerializer

// note tne missing "address2" field!
val jsonString = """
{
  "username":"johnny",
  "email":"[email protected]",
  "addresses":[
    {
      "address1":"195 E. 4th Ave",
      "city":"San Mateo",
      "state":"CA",
      "zip":"94401"
    }
  ],
  "settings":{
    "wantsGeneralNotifications":true,
    "wantsUpdates":true
  }
}
"""

val json = parse(jsonString)
val userObject = json.extract[User]

// write back to json
val jsonString = write(user)

// saving to mongodb with salat

import com.novus.salat._
import com.novus.salat.global._

val dbo = grater[User].asDBObject(user)
userCollection.save(dbo)