如何在Play Json中使用Joda DateTime

Question

我正在开发一个Play应用程序,我正在尝试将Joda DateTime对象用于我的case类.

package model

import org.joda.time.DateTime
import play.api.libs.json._

case class User(name: String, created: DateTime)

object User {
  implicit val yourJodaDateReads = Reads.jodaDateReads("yyyy-MM-dd'T'HH:mm:ss.SSSZ")
  implicit val yourJodaDateWrites = Writes.jodaDateWrites("yyyy-MM-dd'T'HH:mm:ss.SSSZ'")
  implicit val userFormat = Json.format[User]

  def main(args: Array[String]) {

  val value = Json.parse("{ \"name\" : \"hello\" , \"created\" : \"2015-07-16T20:32:04.046+02:00\" }")

  println(Json.toJson(new User("user", new DateTime())))
  println(Json.fromJson(value))
 }
}

基于此解决方案,我收到此错误:

Error:(18, -1) Play 2 Compiler: 
 /activator-1.3.2/notifier-app/app/model/Test.scala:18: ambiguous implicit    values:
 both value yourJodaDateReads in object User of type => play.api.libs.json.Reads[org.joda.time.DateTime]
    and value userFormat in object User of type => play.api.libs.json.OFormat[model.User]

我正在使用Activator 1.3.2和Play 2.3.8.

你能告诉我一下吗？

提前致谢.

更新

我知道play.api.libs.json.Reads中的隐含值存在冲突

implicit val DefaultJodaDateReads = jodaDateReads("yyyy-MM-dd") 

我该如何解决这个问题？

Answer 1

期待更好的选择,在这里我的解决方法:

val dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"

val jodaDateReads = Reads[DateTime](js =>
  js.validate[String].map[DateTime](dtString =>
    DateTime.parse(dtString, DateTimeFormat.forPattern(dateFormat))
  )
)

val jodaDateWrites: Writes[DateTime] = new Writes[DateTime] {
  def writes(d: DateTime): JsValue = JsString(d.toString())
}

val userReads: Reads[User] = (
  (JsPath \ "name").read[String] and
    (JsPath \ "created").read[DateTime](jodaDateReads)
  )(User.apply _)

val userWrites: Writes[User] = (
  (JsPath \ "name").write[String] and
   (JsPath \ "created").write[DateTime](jodaDateWrites)
  )(unlift(User.unapply))

implicit val userFormat: Format[User] = Format(userReads, userWrites)

Answer 2

在游戏2.6中,使用play-json-joda库序列化/反序列化joda DateTime json的规范方法.通过更新您的库来导入库build.sbt.然后像这样创建json reader和json writer:

import play.api.libs.json.JodaWrites
implicit val dateTimeWriter: Writes[DateTime] = JodaWrites.jodaDateWrites("dd/MM/yyyy HH:mm:ss")
import play.api.libs.json.JodaReads
implicit val dateTimeJsReader = JodaReads.jodaDateReads("yyyyMMddHHmmss")

Answer 3

试试这些：

implicit val dateWrites = jodaDateWrites("yyyy-MM-dd'T'HH:mm:ss.SSSZ")
implicit val dateReads = jodaDateReads("yyyy-MM-dd'T'HH:mm:ss.SSSZ")

https://github.com/playframework/playframework/blob/master/framework/src/play-json/src/main/scala/play/api/libs/json/Writes.scala#L411

https://github.com/playframework/playframework/blob/master/framework/src/play-json/src/main/scala/play/api/libs/json/Reads.scala#L645

Answer 4

我知道这个问题已经回答了一段时间，但我找到了一个更简洁的答案

val pattern = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
implicit val dateFormat = Format[DateTime](Reads.jodaDateReads(pattern), Writes.jodaDateWrites(pattern))
implicit val userFormat = Json.format[User]