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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.

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