覆蓋值寫入

Question

假設我有一個JSON這樣寫的

implicit val userWrites: Writes[User] = (
    (__ \ "name").write[String] ~ 
     (__ \ "email").write[String] ~ 
     (__ \ "encryptedPassword").write[String] ~ 
     (__ \ "id").writeNullable[Long] 
    )(unlift(User.unapply)) 

如果我不想打印輸出的密碼，而不是隻打印一個字符串"hidden"，我怎麼可以做到這一點組合子？

我要尋找的是類似於這樣

implicit val userWrites: Writes[User] = (
    (__ \ "name").write[String] ~ 
     (__ \ "email").write[String] ~ 
     (__ \ "encryptedPassword").write[String](Writes.pure("hidden")) ~ 
     (__ \ "id").writeNullable[Long] 
    )(unlift(User.unapply)) 

Answer 1

這應該工作：

implicit val userWrites: Writes[User] = (
    (__ \ "name").write[String] ~ 
     (__ \ "email").write[String] ~ 
     (__ \ "encryptedPassword").write[String](Writes((_: String) => JsString("hidden"))) ~ 
     (__ \ "id").writeNullable[Long] 
    )(unlift(User.unapply)) 

Answer 2

你可以做這樣一個解決方案：

implicit val userWrites = new Writes[User] { 
    override def writes(user: User): JsValue = Json.obj(
    "name" -> user.name, 
    "email" -> user.email, 
    "encryptedPassword" -> "hidden", 
    "id" -> user.id 
) 
}