Play Framework Json sample: Copy JsObject only if passwords equal

gistfile1.scala

import play.api.libs.json._
import play.api.data.validation._
import play.api.libs.functional.syntax._

val json = Json.obj(
  "name" -> "John",
  "email" -> "[email protected]",
  "password" -> "password",
  "confirmPassword" -> "password"
)


val json2 = Json.obj(
  "name" -> "John",
  "email" -> "[email protected]",
  "password" -> "password",
  "confirmPassword" -> "password2"
)


val passwordValidator = __.json.pick[JsObject] keepAnd (
 (
   (__ \ "password").read[String] and
   (__ \ "confirmPassword").read[String]
 ).tupled
  .filter(ValidationError("password not confirmed")){ case(pwd, confPwd) => pwd == confPwd }
)


scala> passwordValidator.reads(json)
res8: play.api.libs.json.JsResult[play.api.libs.json.JsObject] = 
  JsSuccess({"name":"John","email":"[email protected]","password":"password","confirmPassword":"password"},)
  
scala> passwordValidator.reads(json2)
res9: play.api.libs.json.JsResult[play.api.libs.json.JsObject] = 
  JsError(List((,List(ValidationError(password not confirmed,WrappedArray())))))