用于案例对象的Play Framework JSON格式(Play Framework JSON Format for Case Objects)

用于案例对象的Play Framework JSON格式(Play Framework JSON Format for Case Objects)

我有一组继承自特征的案例对象，如下所示：

sealed trait UserRole case object SuperAdmin extends UserRole case object Admin extends UserRole case object User extends UserRole

我想将其序列化为JSON，我只使用了Format机制：

implicit val userRoleFormat: Format[UserRole] = Json.format[UserRole]

但不幸的是，编译器不满意，它说：

No unapply or unapplySeq function found

我的案例对象出了什么问题？

I have a set of case objects that inherits from a trait as below:

sealed trait UserRole case object SuperAdmin extends UserRole case object Admin extends UserRole case object User extends UserRole

I want to serialize this as JSON and I just used the Format mechanism:

implicit val userRoleFormat: Format[UserRole] = Json.format[UserRole]

But unfortunately, the compiler is not happy and it says:

No unapply or unapplySeq function found

What is wrong in my case objects?

最满意答案

好的，我想出了必须要做的事情！

这里是：

implicit object UserRoleWrites extends Writes[UserRole] { def writes(role: UserRole) = role match { case Admin => Json.toJson("Admin") case SuperAdmin => Json.toJson("SuperAdmin") case User => Json.toJson("User") } }

Another option is to override def toString like this:

File: Status.scala

package models trait Status case object Active extends Status { override def toString: String = this.productPrefix } case object InActive extends Status { override def toString: String = this.productPrefix }

this.productPrefix will give you case object name

File: Answer.scala

package models import play.api.libs.json._ case class Answer( id: Int, label: String, status: Status ) { implicit val answerWrites = new Writes[Answer] { def writes(answer: Answer): JsObject = Json.obj( "id" -> answer.id, "label" -> answer.label, "status" -> answer.status.toString ) } def toJson = { Json.toJson(this) } }

File: Controller.scala

import models._ val jsonAnswer = Answer(1, "Blue", Active).toJson println(jsonAnswer)

you get:

{"id":1,"label":"Blue","status":"Active"}

Hope this helps!