Serialization of None Incorrect When In Case Class

Question

Serialization of None Incorrect When In Case Class

Closed this issue 13 years ago · 3 comments

case class Foo(a: Option[String])
val json = generate(Foo(None))

In this code json is set to {} rather than {"a":null}.

It should be as simple as adding this code to CaseClassSerializer.scala:32:

else {
  json.writeFieldName(methodOpt.map {_.getName}.getOrElse(field.getName))
  provider.getNullValueSerializer.serialize(null, json, provider)
}

Answer 1 · 2011-06-22T15:40:42.000Z

Fight it out with @tc: #6

Answer 2 · 2011-06-22T16:30:42.000Z

Is that the canonical way of serializing Option[_]? It seems like it would violate the principle of least surprise to have a None show up as just not being there.

Answer 3 · 2011-06-22T18:46:17.000Z

There is no canonical way of serializing Scala types to JSON values. This is one of many.

As far as things being surprising, mapping a trinary value ("blah", null, or a field which doesn't exist) to a binary value (Some("blah"), None) will always involve collision and thus "surprise."