将包含包含 mutableMap 的对象的大小写 class 转换为 json 并使用 lift 返回

Question

我有一个案例 class 作为 :

case class Cart(cart_id :UUID, cart_entries :Map[String,CartEntry]){

  //override def toString: String = "Saini CartId = " + cart_id.toString

}

我正在使用 net.liftweb.json._ 将其转换为 json :

implicit val formats = Serialization.formats(NoTypeHints) + new UUIDserializer
val json = write(cart)
println(json)

Json 结果为

{"cart_id":"68eb787f-746c-4320-9ef4-8b5c7f0d7e21","cart_entries":[{"_1":"ABC","_2":{"sku_id":"ABC","quantity":12,"price":213.0}}]}

将我的 json 转换回购物车对象时 :

val jValue = read[Cart](json)

我遇到了这个异常。

[ERROR] [12/22/2016 17:11:23.784] [System-akka.actor.default-dispatcher-3] [akka://System/user/68eb787f-746c-4320-9ef4-8b5c7f0d7e21] No usable value for cart_entries No constructor for type interface scala.collection.mutable.Map, JArray(List(JObject(List(JField(_1,JString(ABC)), JField(_2,JObject(List(JField(sku_id,JString(ABC)), JField(quantity,JInt(12)), JField(price,JDouble(213.0))))))))) net.liftweb.json.MappingException: No usable value for cart_entries No constructor for type interface scala.collection.mutable.Map, JArray(List(JObject(List(JField(_1,JString(ABC)), JField(_2,JObject(List(JField(sku_id,JString(ABC)), JField(quantity,JInt(12)), JField(price,JDouble(213.0))))))))) at net.liftweb.json.Meta$.fail(Meta.scala:191) at net.liftweb.json.Extraction$.mkValue(Extraction.scala:357) at net.liftweb.json.Extraction$.net$liftweb$json$Extraction$$build(Extraction.scala:317) at net.liftweb.json.Extraction$$anonfun.apply(Extraction.scala:253) at net.liftweb.json.Extraction$$anonfun.apply(Extraction.scala:253) at scala.collection.immutable.List.map(List.scala:277) at net.liftweb.json.Extraction$.instantiate(Extraction.scala:253) at net.liftweb.json.Extraction$.newInstance(Extraction.scala:286) at net.liftweb.json.Extraction$.net$liftweb$json$Extraction$$build(Extraction.scala:315) at net.liftweb.json.Extraction$.net$liftweb$json$Extraction$$extract0(Extraction.scala:366) at net.liftweb.json.Extraction$.net$liftweb$json$Extraction$$extract0(Extraction.scala:199) at net.liftweb.json.Extraction$.extract(Extraction.scala:43) at net.liftweb.json.JsonAST$JValue.extract(JsonAST.scala:312) at net.liftweb.json.Serialization$.read(Serialization.scala:58) at What should i do ?

Answer 1

您的 cart_entries 字段定义为 scala.collection.mutable.Map。 Lift 的 JSON 序列化知道如何序列化 Map（可变或不可变），但它不知道如何反序列化为可变 Map。要修复它，请将您的地图定义为 scala.collection.immutable.Map 或将 TypeHints 添加到您的格式以支持可变类型。

将包含包含 mutableMap 的对象的大小写 class 转换为 json 并使用 lift 返回

Convert case class containing objects containing mutableMap to json and back using lift

json

lift

mutablemap