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Friday, October 5, 2012

Using Play JSON library to expose JSON services

Currently I am experimenting with Playframework. Today we will see how easy it is to generate a JSON response. Let us first take a look at our domain model
package models

case class Contact(firstName: String, lastName: String, age: Int)

object Contact {
  val contacts = Set(
      Contact("Robby", "Pelssers", 35),
      Contact("Davy", "Pelssers", 35),
      Contact("Lindsey", "Pelssers", 9)
  def findAll = this.contacts.toList.sortBy(_.firstName)

Next let us take a look at a simple controller returning contacts in JSON format
package controllers

import play.api.mvc.{ Action, Controller }
import play.api.libs.json.Json._
import models.Contact

object Contacts extends Controller {

  def toJSON = Action { implicit request =>
    val contacts = Contact.findAll   
    val json = 
            contact => toJson(
                Map("firstName" -> toJson(contact.firstName), 
                    "lastName" -> toJson(contact.lastName), 
                    "age" -> toJson(contact.age))

Now it's a matter of mapping a URL to our controller method.
GET     /contacts.json              controllers.Contacts.toJSON
Now let's see if our response looks ok by using curl
$ curl --request GET --include http://localhost:9000/contacts.json
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Content-Length: 160


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