Combining type and field serializers

Question

Let\'s assume I have a case class with the following setup:

case class Place(id:java.util.UUID, name:String)

I can write a (working!) seria

Answer 1

The trick is to not write a serializer for your type, but for the type that you're using inside (in this case java.util.UUID)

Then you can add that serializer to the toolbox and from then any type using UUID will work exactly like types using DefaultSerializer supported fields did:

case object UUIDSerialiser extends CustomSerializer[UUID](format => (
    {
      case JString(s) => UUID.fromString(s)
      case JNull => null
    },
    {
      case x: UUID => JString(x.toString)
    }
  )
)

implicit val json4sFormats = Serialization.formats(NoTypeHints) + UUIDSerialiser

Update link to the PR

Update 2 the PR was merged, and now, in case of UUID you can use:

import org.json4s.ext.JavaTypesSerializers

implicit val json4sFormats = Serialization.formats(NoTypeHints) ++ JavaTypesSerializers.all

Answer 2

There is now a UUID serializer provided in the extras package of json4s. It will most likely be available in version 3.2.11 (which has not been released as of this writing).

You'll be able to do something like this:

import org.json4s.ext.JavaTypesSerializers

implicit val json4sFormats = Serialization.formats(NoTypeHints) ++ JavaTypesSerializers.all

This was taken from the tests for this feature's PR.