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author | Performant Data <performantdata@users.noreply.github.com> | 2017-07-23 00:44:18 -0700 |
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committer | GitHub <noreply@github.com> | 2017-07-23 00:44:18 -0700 |
commit | 1c1b3cbb30bc54f1f975f3afd924d6d023252a0f (patch) | |
tree | c29ead5fbb21549dbab0d5b9866eab75ef95e745 /README.markdown | |
parent | 8a421f066e99359a3d6fa4cd64cded206376d264 (diff) | |
download | spray-json-1c1b3cbb30bc54f1f975f3afd924d6d023252a0f.tar.gz spray-json-1c1b3cbb30bc54f1f975f3afd924d6d023252a0f.tar.bz2 spray-json-1c1b3cbb30bc54f1f975f3afd924d6d023252a0f.zip |
document how unboxed classes should be handled
Diffstat (limited to 'README.markdown')
-rw-r--r-- | README.markdown | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/README.markdown b/README.markdown index e659e71..a8a7d9d 100644 --- a/README.markdown +++ b/README.markdown @@ -219,6 +219,38 @@ 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 + +```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 |