启用 DefaultTyping 时，Scala 枚举序列化使用 Jackson 失败

Question

我看到当 DefaultTyping 启用了 OBJECT_AND_NON_CONCRETE 时，Jackson 库无法序列化 Scala 枚举。环境。请注意，当我使用 JAVA_LANG_OBJECT 时，序列化工作正常环境。

我看到以下异常

[scalatest]   com.fasterxml.jackson.databind.JsonMappingException: Type id handling not implemented for type scala.Enumeration$Val (by serializer of type com.fasterxml.jackson.module.scala.ser.EnumerationSerializer) (through reference chain: <MyType>)
[scalatest]   at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:284)
[scalatest]   at com.fasterxml.jackson.databind.SerializerProvider.mappingException(SerializerProvider.java:1110)
[scalatest]   at com.fasterxml.jackson.databind.SerializerProvider.reportMappingProblem(SerializerProvider.java:1135)
[scalatest]   at com.fasterxml.jackson.databind.JsonSerializer.serializeWithType(JsonSerializer.java:160)
[scalatest]   at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:706)
[scalatest]   at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689)
[scalatest]   at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
[scalatest]   at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:292)
[scalatest]   at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:2509)
[scalatest]   at com.fasterxml.jackson.core.base.GeneratorBase.writeObject(GeneratorBase.java:378)

这是一个示例代码

  object Day extends Enumeration {
    val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
  }

  case class Holiday(day: Day.Value)

  val objectMapper = new ObjectMapper()
  objectMapper.registerModule(DefaultScalaModule)
  objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
  objectMapper.configure(DeserializationFeature.FAIL_ON_INVALID_SUBTYPE, false)
  objectMapper.enableDefaultTyping(DefaultTyping.OBJECT_AND_NON_CONCRETE, JsonTypeInfo.As.PROPERTY)

我试过使用 @JsonScalaEnumeration如 https://github.com/FasterXML/jackson-module-scala/wiki/Enumerations 中所述，但似乎没有帮助。

提前致谢。

Answer 1

我用这样的解决方法让它工作

  object Day extends Enumeration {
    type Day = Value
    //val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
    case class Val(dayName: String) extends super.Val

    val Mon = Val("Monday")
    val Tue = Val("Tuesday")
    val Sat = Val("Saturday")
    val Sun = Val("Sunday")
  }

  class DayType extends TypeReference[Day.type]

  case class Holidays(@JsonScalaEnumeration(classOf[DayType]) days: Day.Val)