大家好,我在circe库和在scala case类之间进行转换的circe库遇到问题,我们将不胜感激。
过去我有这样的ADT。
sealed trait Sons
case class Son1(name: String, belongings: List[String]) extends Sons
case class Son2(lastName: String, belongings: List[String]) extends Sons
并且没有任何问题,但是由于设计原因,现在更改该特性的代价很高,我们必须从特性中删除密封,因此现在有了这个特性(儿子在不同的文件/库中)
trait Sons
case class Son1(name: String, belongings: List[String]) extends Sons
case class Son2(lastName: String, belongings: List[String]) extends Sons
尝试将Scala的儿子列表转换为json时,库在列表产生问题之前将::放在该示例中可以看到的问题。
object Test extends App{
implicit val encoderSon1: Encoder[Son1]=deriveEncoder[Son1]
implicit val decoderSon1: Decoder[Son1]=deriveDecoder[Son1]
implicit val encoderSon2: Encoder[Son2]=deriveEncoder[Son2]
implicit val decoderSon2: Decoder[Son2]=deriveDecoder[Son2]
implicit val encoderSon: Encoder[Sons] = Encoder.instance {
case son1: Son1 => son1.asJson
case son2: Son2 => son2.asJson
}
implicit val DecoderSon: Decoder[Sons] =
List[Decoder[Sons]](
Decoder[Son1].widen,
Decoder[Son2].widen
).reduceLeft(_ or _)
implicit val encoderSonList: Encoder[List[Sons]] = deriveEncoder
implicit val DecoderSonList: Decoder[List[Sons]] = deriveDecoder
val sonsList: List[Sons] = List(Son1("James",List()),Son2("Mike",List()))
println(s"1->${sonsList}")
println(s"2->${sonsList.asJson.noSpaces}")
val andBack=decode[List[Sons]](sonsList.asJson.noSpaces).fold(fa=>fa.getMessage,fb=>fb.toString())
println(s"3->${andBack}")
}
印刷品正在印刷
1->List(Son1(James,List()), Son2(Mike,List()))
2->{"::":[{"name":"James","belongings":[]},{"lastName":"Mike","belongings":[]}]}
3->Attempt to decode value on failed cursor: DownField(head),DownField(::)
问题是,当转换为JSON时,我当然不希望将列表放在::字段中。
谢谢您的任何可能的帮助:D
Don't use semi auto for
List
- semiauto uses slightly different mechanism than other derivations to e.g. avoid issues like:For that reason when you are using semiauto here,
List
instances fromEncoder
andDecoder
are ignored, and instead macro generates code forList
ADT - that iscase class ::
andcase object Nil
.如果删除
它会再次工作。