在Scala循环json库中不能用LocalDateTime的自定义解码器反序列化对象

Question

我试图为LocalDateTime对象的case类添加自定义反序列化器，但是它从circe-java8模块中提取默认反序列化器。如果删除此模块，代码将无法编译(找不到用于LocalDateTime的反序列化程序)

sbt

"io.circe" %% "circe-core" % circeVersion,
"io.circe" %% "circe-generic" % circeVersion,
"io.circe" %% "circe-parser" % circeVersion,
"io.circe" %% "circe-optics" % circeVersion,
"io.circe" %% "circe-java8" % circeVersion,

和带有自定义LocalDateTime序列化程序/反序列化器的源代码。

case class A(
  date: LocalDateTime,
)

object A {
  val formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
  implicit val dateEncoder = Encoder.encodeString.contramap[LocalDateTime](_.format(formatter))
  implicit val dateDecoder = Decoder.decodeString.emap[LocalDateTime](str => {
    Either.catchNonFatal(LocalDateTime.parse(str, formatter)).leftMap(_.getMessage)
  })
}

如何将对象A中指定的A对象的自定义反序列化器应用于A case类？

Answer 1

A使用半自动派生

import io.circe.generic.semiauto._

case class A(
  date: LocalDateTime,
)

object A {
  val formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
  implicit val dateEncoder = Encoder.encodeString.contramap[LocalDateTime](_.format(formatter))
  implicit val dateDecoder = Decoder.decodeString.emap[LocalDateTime](str => {
    Either.catchNonFatal(LocalDateTime.parse(str, formatter)).leftMap(_.getMessage)
  })
  implicit val AEncoder = deriveEncoder[A]
  implicit val ADecoder = deriveDecoder[A]
}