4

整个下午我一直在努力解决这个问题，但无济于事，Play 2.1.1 彻底改变了 Json 读写的工作方式。

基本上我有一个看起来像这样的包装器对象：

case class CombinedUser(user: SocialUser, userdetails: UserDetails)

如您所见，它包含 2 个我想要序列化和反序列化为 json 的类。

但我不明白如何使用新设计获取和设置子类中的字段。

例如

implicit val combinedUser2Reads = (
  (__ \ "email").read[String] and
  (__ \ "providerid").read[String] and
  (__ \ "firstname").read[String] and
  (__ \ "lastname").read[String] and
  (__ \ "fullname").read[String] and
  (__ \ "avatarurl").read[String] and
  (__ \ "address1").read[String] and
  (__ \ "address2").read[String] and
  (__ \ "address3").read[String] and
  (__ \ "city").read[String] and
  (__ \ "country").read[String] and
  (__ \ "phone").read[String] and
  (__ \ "publickey").as[String]
)(CombinedUser2.apply _)

我想要一个包含大部分子类字段的json blob，所有字符串。

因为它使用了应用的东西，所以我看不到如何在映射之前创建子类。

非常感谢任何帮助或指导。

谢谢

汤姆

4

1 回答 1

8

你可以这样做：

case class SocialUser(firstName: String, lastName: String)
case class UserDetails(avatarUrl: String, phone: String)
case class CombinedUser(user: SocialUser, userDetails: UserDetails)  
implicit val combinedUserReads: Reads[CombinedUser] = (
  (__ \ "user").read((
    (__ \ "firstName").read[String] and
    (__ \ "lastName").read[String]
  )(SocialUser)) and
  (__ \ "userDetails").read((
    (__ \ "avatarUrl").read[String] and
    (__ \ "phone").read[String]
  )(UserDetails))
)(CombinedUser)

但是最好创建分离Reads：

implicit val socialUserReads = (
  (__ \ "firstName").read[String] and
  (__ \ "lastName").read[String]
)(SocialUser)    
implicit val userDetailsReads = (
  (__ \ "avatarUrl").read[String] and
  (__ \ "phone").read[String]
)(UserDetails)
implicit val combinedUserReads: Reads[CombinedUser] = (
  (__ \ "user").read[SocialUser] and
  (__ \ "userDetails").read[UserDetails]
)(CombinedUser)

编辑：对于简单的案例类，可以这样做：

implicit val socialUserReads = Json.format[SocialUser]
implicit val userDetailsReads = Json.format[UserDetails]
implicit val combinedUserReads = Json.format[CombinedUser]

这是对 JSON Reads 等的相当全面的介绍。

部分对象呢？如果我不想填写构造函数中的每个字段，我可以传递空值还是重载构造函数或类似内容？

使用Option：

case class CombinedUser(user: SocialUser, userDetails: Option[UserDetails])
//reads
implicit val combinedUserReads: Reads[CombinedUser] = (
  (__ \ "user").read[SocialUser] and
  (__ \ "userDetails").readOpt[UserDetails]
)(CombinedUser)
//writes
implicit val combinedUserWrites: Writes[CombinedUser] = (
  //socialUserWrites and userDetailsWrites must be in scope
  (__ \ "user").write[SocialUser] and
  (__ \ "userDetails").write[Option[UserDetails]]
)(unlift(CombinedUser.unapply))

val json = Json.obj(
  "user" -> Json.obj(
    "firstName" -> "Homer",
    "lastName" -> "Simpson"
  )
)
Json.fromJson[CombinedUser](json)
//JsSuccess(CombinedUser(SocialUser(Homer,Simpson),None),)
于 2013-04-15T18:10:55.170 回答