带有case类的抽象类的scala circe编码器/解码器

我想将FieldMapping类的集合保存为json字符串-

abstract class Field {
  def clazz: Class[_]

  def name: String
}

case class StringField(name: String) extends Field {
  override def clazz: Class[_] = classOf[String]
}

case class DateField(name: String) extends Field {
  override def clazz: Class[_] = classOf[Date]
}

。。。etc-此处的完整代码：

Circe代码：

import com.example.model.{DateField, Field, FieldMapping, StringField}
import io.circe.generic.semiauto.{deriveDecoder, deriveEncoder}
import io.circe.{Decoder, Encoder}

object CirceBoilerplateForConfigs {
  implicit val fieldDecoder: Decoder[StringField] = deriveDecoder[StringField]
  implicit val fieldEncoder: Encoder[StringField] = deriveEncoder[StringField]

  implicit val dateDecoder: Decoder[DateField] = deriveDecoder[DateField]
  implicit val dateEncoder: Encoder[DateField] = deriveEncoder[DateField]

  implicit val fooDecoder: Decoder[FieldMapping] = deriveDecoder[FieldMapping]
  implicit val fooEncoder: Encoder[FieldMapping] = deriveEncoder[FieldMapping]
}

错误：（14，65）找不到类型为的惰性隐式值 io.circe.generic.decoding.DerivedDecoder[com.example.model.FieldMapping] 隐式val FoodDecoder:解码器[字段映射]= deriveDecoder[FieldMapping]错误：（14,65）

没有足够的参数用于方法deriveDecoder:（隐式解码： shapless.Lazy[io.circe.generic.decoding.DerivedDecoder[com.example.model.FieldMapping]]）io.circe.Decoder[com.example.model.FieldMapping]。 未指定值的参数解码。隐式val-FoodDecoder： 解码器[FieldMapping]=deriveDecoder[FieldMapping]错误：（15,65）

找不到类型为的惰性隐式值 io.circe.generic.encoding.DerivedObjectEncoder[com.example.model.FieldMapping] 隐式val fooEncoder:编码器[字段映射]= deriveEncoder[FieldMapping]错误：（15,65）

没有足够的论据支持 方法deriveEncoder：（隐式编码： shapeless.Lazy[io.circ.generic.encoding.DerivedObjectEncoder[com.example.model.FieldMapping]]）io.circ.ObjectEncoder[com.example.model.FieldMapping]。 未指定的值参数编码。隐式val编码器： 编码器[FieldMapping]=deriveEncoder[FieldMapping]

---

字段

应为密封特征（对于抽象类或非密封特征，这将不起作用）

编译以下代码：

import java.util.Date

sealed trait Field {
  def clazz: Class[_]

  def name: String
}

case class StringField(name: String) extends Field {
  override def clazz: Class[_] = classOf[String]
}

case class DateField(name: String) extends Field {
  override def clazz: Class[_] = classOf[Date]
}

case class FieldMapping(fieldInConnector1: Option[Field],
                        fieldInConnector2: Option[Field],
                        selected: Boolean,
                        defaultValue: String)

import io.circe.generic.semiauto.{deriveDecoder, deriveEncoder}
import io.circe.{Decoder, Encoder}
object CirceBoilerplateForConfigs {
  implicit val stringDecoder: Decoder[StringField] = deriveDecoder[StringField]
  implicit val stringEncoder: Encoder[StringField] = deriveEncoder[StringField]

  implicit val dateDecoder: Decoder[DateField] = deriveDecoder[DateField]
  implicit val dateEncoder: Encoder[DateField] = deriveEncoder[DateField]

  implicit val fieldDecoder: Decoder[Field] = deriveDecoder[Field]
  implicit val fieldEncoder: Encoder[Field] = deriveEncoder[Field]

  implicit val fooDecoder: Decoder[FieldMapping] = deriveDecoder[FieldMapping]
  implicit val fooEncoder: Encoder[FieldMapping] = deriveEncoder[FieldMapping]
}

---

在您的要点中，您没有为

GUser

提供代码

字段映射

也没有定义。如果我注释掉

case class GUserField

，

def user

，

导入com.example.model…

，

隐式val-fooDecoder>，
implicit val foocoder
一切都会编译。下面是代码的其余部分-我需要用于FieldMapping集合的编码器/解码器，因为这是我想要转换为json字符串的内容