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diff --git a/README.markdown b/README.markdown index b62918e..30ca8ed 100644 --- a/README.markdown +++ b/README.markdown @@ -220,6 +220,38 @@ object MyJsonProtocol extends DefaultJsonProtocol { This is a bit more verbose in its definition and the resulting JSON but transports the field semantics over to the JSON side. Note that this is the approach _spray-json_ uses for case classes. +### Providing JsonFormats for unboxed types + +A value class + +```scala +case class PhoneNumber(value: String) extends AnyVal +val num = PhoneNumber("+1 212 555 1111") +``` + +or a class with multiple members + +```scala +case class Money(currency: String, amount: BigDecimal) +val bal = Money("USD", 100) +``` + +can be handled as above with `jsonFormatX`, etc. +It may be preferable, however, to serialize such instances without object boxing: +as `"USD 100"` instead of `{"currency":"USD","amount":100}`. +This requires explicit (de)serialization logic: + +```scala +implicit object MoneyFormat extends JsonFormat[Money] { + val fmt = """([A-Z]{3}) ([0-9.]+)""".r + def write(m: Money) = JsString(s"${m.currency} ${m.amount}") + def read(json: JsValue) = json match { + case JsString(fmt(c, a)) => Money(c, BigDecimal(a)) + case _ => deserializationError("String expected") + } +} +``` + ### JsonFormat vs. RootJsonFormat |