播放JSON讀取錯誤當讀取一個序列

Question

我有以下的情況下類：

case class VirtualAssetConfigParam(
    id: Long, 
    pMin: Double, 
    pMax: Double, 
    dispatchPriority: Int 
) 

object VirtualAssetConfigParam { 

    implicit val virtualAssetConfigParamReads: Reads[VirtualAssetConfigParam] = (
    (JsPath \ "id").read[Long] and 
     (JsPath \ "power_min").read[Double] and 
     (JsPath \ "power_max").read[Double] and 
     (JsPath \ "dispatch_priority").read[Int] 
    )(VirtualAssetConfigParam.apply _) 
} 

這是我從數據庫中獲取的JSON：

[{"id":"1","power_min":"200","power_max":"400","dispatch_priority":"1"},{"id":"2","power_min":"200","power_max":"400","dispatch_priority":"2"},{"id":"3","power_min":"-700","power_max":"0","dispatch_priority":"3"}] 

當我試圖驗證它作爲（其中virtualAssetConfigParam是一個字符串，我從數據庫中獲取）：

Json.parse(virtualAssetConfigParam).validate[List[VirtualAssetConfigParam]] 

我碰到下面的驗證RESU lt：

JsError(
    List(
     ((0)/dispatchPriority,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((0)/pMin,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((0)/pMax,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((0)/id,List(ValidationError(List(error.expected.jsnumber),WrappedArray()))), 
     ((1)/dispatchPriority,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((1)/pMin,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((1)/pMax,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((1)/id,List(ValidationError(List(error.expected.jsnumber),WrappedArray()))), 
     ((2)/dispatchPriority,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((2)/pMin,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((2)/pMax,List(ValidationError(List(error.path.missing),WrappedArray()))), 
     ((2)/id,List(ValidationError(List(error.expected.jsnumber),WrappedArray()))) 
    ) 
) 

什麼問題？我看不出爲什麼這會失敗！

Answer 1

JSON中的數據類型與案例類中的預期數據類型不匹配。所以，案例類應爲：

implicit val virtualAssetConfigParamReads: Reads[VirtualAssetConfigParam] = new Reads[VirtualAssetConfigParam] { 
    override def reads(json: JsValue): JsResult[VirtualAssetConfigParam] = { 
     JsSuccess(VirtualAssetConfigParam(
     (json \ "id").as[String].toLong, 
     (json \ "power_min").as[String].toDouble, 
     (json \ "power_max").as[String].toDouble, 
     (json \ "dispatch_priority").as[String].toInt 
    )) 
    } 
    } 

當我現在請JSON解析功能，我不喜歡這樣寫道：

Try((Json.parse(json)).validate[Seq[VirtualAssetConfigParam]]) 

，然後折上的嘗試成功了！

Answer 2

看一看我的博客張貼在不久前，它可以幫助你：

http://pedrorijo.com/blog/scala-json/

和

http://pedrorijo.com/blog/scala-json-part2/

Answer 3

如果你看一下你的錯誤，你會發現，它正試圖找到路徑 - dispatchPriority,pMin,pMax和id這是不同於你想要在你的01路徑。這表示您在代碼中顯示的讀取實現未在此處使用。

這讓我想到，可能你並沒有將你的隱式讀入導入你的代碼範圍。

case class VirtualAssetConfigParam(
    id: Long, 
    pMin: Double, 
    pMax: Double, 
    dispatchPriority: Int 
) 

object VirtualAssetConfigParam { 

    implicit val virtualAssetConfigParamReads: Reads[VirtualAssetConfigParam] = (
    (JsPath \ "id").read[Long] and 
    (JsPath \ "power_min").read[Double] and 
    (JsPath \ "power_max").read[Double] and 
    (JsPath \ "dispatch_priority").read[Int] 
)(VirtualAssetConfigParam.apply _) 

} 

object Demo extends App { 

    // I think you are missing this import 
    import VirtualAssetConfigParam.virtualAssetConfigParamReads 

    val virtualAssetConfigParam = [{"id":"1","power_min":"200","power_max":"400","dispatch_priority":"1"},{"id":"2","power_min":"200","power_max":"400","dispatch_priority":"2"},{"id":"3","power_min":"-700","power_max":"0","dispatch_priority":"3"}] 

// It should work if you have that import 
val jsonValidate = Json.parse(virtualAssetConfigParam).validate[List[VirtualAssetConfigParam]] 


}