Converting DateTime to a JSON string - json

Question

I want to convert a case class with an Option[DateTime] parameter to a spray-json object which can be served by an API. Using spray-json I have a custom JsonFormat as such
object JsonImplicits extends DefaultJsonProtocol {
implicit object PostJsonFormat extends RootJsonFormat[Post] {
def write(p: Post) = JsObject(
"title" -> JsString(p.title),
"content" -> JsString(p.content),
"author" -> JsString(p.author),
"creationDate" -> JsString(p.creationDate.getOrElse(DateTime.now))
)
}
}
But I get:
overloaded method value apply with alternatives:
(value: String)spray.json.JsString <and>
(value: Symbol)spray.json.JsString
cannot be applied to (com.github.nscala_time.time.Imports.DateTime)
"creationDate" -> JsString(p.creationDate.getOrElse(DateTime.now))
when I try to compile it and no matter what I try I can't seem to convert the DateTime object to a string. For instance, when I try calling toString I get
ambiguous reference to overloaded definition,
both method toString in class AbstractDateTime of type (x$1: String, x$2: java.util.Locale)String
and method toString in class AbstractDateTime of type (x$1: String)String
match expected type ?
"creationDate" -> JsString(p.creationDate.getOrElse(DateTime.now.toString)))

Answer 1

You have several problems here.
First, the toString() method in AbstractDateTime requires one or several arguments see here.
But I would advise you against this path and recommend using properly Spray-Json.
Spray-json does not know how to serialize Option[DateTime], therefore you have to provide a RootJsonFormat for it.
This is what I am doing.
implicit object DateJsonFormat extends RootJsonFormat[DateTime] {
private val parserISO : DateTimeFormatter = ISODateTimeFormat.dateTimeNoMillis();
override def write(obj: DateTime) = JsString(parserISO.print(obj))
override def read(json: JsValue) : DateTime = json match {
case JsString(s) => parserISO.parseDateTime(s)
case _ => throw new DeserializationException("Error info you want here ...")
}
}
Adapt it as you want if you do not want to use ISO formatting.