unable to understand why validateOpt will return `None` instead of `JsError` - playframework-2.6

Question

In the following code, I am unable to understand why validateOpt might return value JsSuccess(None) instead of JsError
def getQuestion = silhouette.UserAwareAction.async{
implicit request => {
val body: AnyContent = request.body
val jsonBodyOption: Option[JsValue] = body.asJson
jsonBodyOption.map((jsonBody:JsValue) => { //body is json
val personJsonJsResultOption = jsonBody.validateOpt[Person]//check that json structure is correct
personJsonJsResultOption match {
case personSuccessOption: JsSuccess[Option[Person]] => { //json is correct
val personOption = personSuccessOption.getOrElse(None) //why would getOrElse return None??
personOption match {
case Some(person) => {
... }
case None =>{ //I am not sure when this will be triggered.
...
}
}
}
}
case e: JsError => {
...
}
}
}
})
.getOrElse(//body is not json
...)
}
}

Answer 1

validateOpt by design considers success to be not only when body provides actual Person but also when Person is null or not provided. Note how documentation explains why JsSuccess(None) is returned:
/**
* If this result contains `JsNull` or is undefined, returns `JsSuccess(None)`.
* Otherwise returns the result of validating as an `A` and wrapping the result in a `Some`.
*/
def validateOpt[A](implicit rds: Reads[A]): JsResult[Option[A]]
Seems like your requirement is that Person must always be provided to be considered successful, so in this case validate should be used instead of validateOpt.