Spray(4)spray-json

Spray(4)spray-json
Installation
It is available from the repository and based on sbt.
"spray repo" at "http://repo.spray.io/",
"io.spray" % "spray-json_2.10" % "1.2.3",

Sometimes there is a trailing "cross CrossVersion.full" modifier for SBT 0.12.x

Check my version
>sbt sbt-version
0.12.1

Usage
First of all, Import the packages
import spray.json._
import spray.httpx.SprayJsonSupport

Define the Object
object EnumSex extends Enumeration {
type Sex = Value
val MALE = Value("MALE")
val FEMALE = Value("FEMALE")
}

case class Address(streetNumber: String, street: String, city: String)

case class Person(userName: String, age: Int, sex: EnumSex.Sex, address: Address)

case class Color(name: String, red: Int, green: Int, blue: Int)

Then I can parse the string to AST abstract Syntax Tree(AST).

1. String to AST
valjson1 = """{ "streetNumber": "A1", "street" : "Main Street", "city" : "Colombo" }"""
valjson2 = """{ "name" : "John", "age" : 26, "sex" : 0 , "address" : { "streetNumber": "A1", "street" : "Main Street", "city" : "Colombo" }}"""

//string to AST
valaddressAST = json1.asJson //or JsonParser(source)
valpersonAST = json2.asJson

2. AST to String
//AST to string
println(addressAST.compactPrint) //or .compactPrint
println(personAST.prettyPrint)

3. AST to Object
import AddressJsonProtocol._
//AST 2 Object
val address1 = addressAST.convertTo[Address]

4. Object to AST
//Object 2 AST
valaddressAST2 = address1.toJson

Some other examples:
import ColorProtocol._
//Object 2 AST
val colorAST = Color("CadetBlue", 95, 158, 160).toJson

//AST 2 Object
val color1 = colorAST.convertTo[Color]

For the step3 and step4, we can not directly use that. We need to implement and import the DefaultJsonProtocol.

object ColorProtocol extends DefaultJsonProtocol {
implicit val colorFormat = jsonFormat4(Color)
}

object AddressJsonProtocol extends DefaultJsonProtocol with SprayJsonSupport {
implicit object AddressJsonFormat extends RootJsonFormat[Address] {
def write(address: Address) = JsObject(
"streetNumber" -> JsString(address.streetNumber),
"street" -> JsString(address.street),
"city" -> JsString(address.city))
def read(jsAddress: JsValue) = {
jsAddress.asJsObject.getFields("streetNumber", "street", "city") match {
case Seq(JsString(streetNumber), JsString(street), JsString(city)) =>
new Address(streetNumber, street, city)
case _ => throw new DeserializationException("Address expected")
}
}
}
}

References:
https://github.com/spray/spray-json
https://github.com/jestan/spray-json-examples