json deserializer with support for parameterized Case Classes

Question

Just encountered that liftweb.json does not work with parameterized Case Classes. The following fails at runtime:

case class ResponseOrError[R](status: String, responseData: Option[R], exception: Option[Error]) {
}

val answer = json.extract[ResponseOrError[Response]]

with:

do not know how to get type parameter from R

Is there any JSON deserializer, which actually works with parameterized Case Classes?

Answer 1

json4s works the way you expect. Here is an example:

import org.json4s.{DefaultFormats, Formats}
import org.json4s.jackson.JsonMethods.parse

case class Z(str: String)
case class X[R](z: Option[R])

val json =
  """
    |{
    |    "z": {
    |        "str" : "test"
    |    }
    |}
  """.stripMargin

implicit val formats: Formats = DefaultFormats.withStrictArrayExtraction

val result = parse(json).extract[X[Z]]
println(result)

output

X(Some(Z(test)))