How to handle optional fields in JSON parsing in play 2.1 - scala

Question

I'm using the new Play 2.1-RC1 framework and I have a class that has an Option[] field, something like this:
import play.api.libs.json._
import play.api.libs.json.util._
import play.api.libs.json.Reads._
import play.api.libs.json.Writes._
import play.api.libs.json.Format._
import play.api.libs.functional.syntax._
case class Test(name: String, value: Option[String])
object Test {
implicit val testFormat = (
(__ \ "name").format[String] and
(__ \ "value").format[Option[String]]
)(Test.apply, unlift(Test.unapply))
def fromJson(js: String): Test = {
Json.fromJson[Test](Json.parse(js)).fold(
valid = { t => t},
invalid = { e => {
val missingField = (e(0)._1).toString.substring(1)
val badJs = js.trim
val newJs = badJs.substring(0, badJs.length()-1)+",\""+missingField+"\":null}"
fromJson(newJs)
}}
)
}
}
I want to be able to handle JSON strings that omit the optional "value" data, e.g.
val y = """{"name":"someone"}"""
(edited question)
I can rewrite the json string (rather clumsily) as shown in the validation step, but
is there a simpler pattern I can use to supply None for missing Optional fields? Note that this rewrite does not work with nested structures, or anywhere where I can't simply append the missing field.

Answer 1

You can simply do this:
import play.api.libs.json._
import play.api.libs.functional.syntax._
case class Test(name: String, value: Option[String])
implicit val testFormat = Json.format[Test]
def hoge = Action(Json.parse.json) { request =>
Json.fromJson[Test](request.body)
...
}

Answer 2

OK ... so the answer is very simple. Use
fomatOpt()
for optional fields. So the test formatter now looks like this:
import play.api.libs.json._
import play.api.libs.json.util._
import play.api.libs.json.Reads._
import play.api.libs.json.Writes._
import play.api.libs.json.Format._
import play.api.libs.functional.syntax._
case class Test(name: String, value: Option[String])
object Test {
implicit val testFormat = (
(__ \ "name").format[String] and
(__ \ "value").formatOpt[String]
)(Test.apply, unlift(Test.unapply))
def fromJson(js: String): Test = {
Json.fromJson[Test](Json.parse(js)).fold(
valid = { t => t},
invalid = { e => {
println("BAD JSON!")
null
}}
)
}
}