使用play-json轉換JsArray

Question

json轉換器中的大多數示例都是關於JsObject的。我試着改造的JsArray但得到這個錯誤

val json = Json.parse("""[{"toto":1},{"toto":10},{"tata":2}]"""] 


val transformer = (__ \'toto).json.update(__.read[JsNumber].map{o => JsNumber(3)}) 

json.as[JsArray].map(_.transform(transformer)) 

錯誤

java.lang.RuntimeException: expected KeyPathNode 
    at play.api.libs.json.JsPath$.step$1(JsPath.scala:147) 
    at play.api.libs.json.JsPath$.play$api$libs$json$JsPath$$buildSubPath$1(JsPath.scala:156) 
    at play.api.libs.json.JsPath$$anonfun$createObj$1.apply(JsPath.scala:161) 
    at play.api.libs.json.JsPath$$anonfun$createObj$1.apply(JsPath.scala:159) 
    at scala.collection.IndexedSeqOptimized$class.foldl(IndexedSeqOptimized.scala:57) 
    at scala.collection.IndexedSeqOptimized$class.foldLeft(IndexedSeqOptimized.scala:66) 
    at scala.collection.mutable.WrappedArray.foldLeft(WrappedArray.scala:35) 
    at play.api.libs.json.JsPath$.createObj(JsPath.scala:159) 
    at play.api.libs.json.PathReads$$anonfun$jsUpdate$1$$anonfun$apply$15.apply(JsConstraints.scala:86) 
    at play.api.libs.json.PathReads$$anonfun$jsUpdate$1$$anonfun$apply$15.apply(JsConstraints.scala:86) 
    at play.api.libs.json.JsResult$class.map(JsResult.scala:81) 
    at play.api.libs.json.JsSuccess.map(JsResult.scala:9) 
    at play.api.libs.json.PathReads$$anonfun$jsUpdate$1.apply(JsConstraints.scala:86) 
    at play.api.libs.json.PathReads$$anonfun$jsUpdate$1.apply(JsConstraints.scala:82) 
    at play.api.libs.json.Reads$$anon$8.reads(Reads.scala:101) 
    at play.api.libs.json.JsValue$class.transform(JsValue.scala:78) 
    at play.api.libs.json.JsObject.transform(JsValue.scala:166) 
    at $anonfun$1.apply(<console>:21) 
    at $anonfun$1.apply(<console>:21) 
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245) 
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245) 
    at scala.collection.immutable.List.foreach(List.scala:381) 
    at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35) 
    at scala.collection.mutable.ListBuffer.foreach(ListBuffer.scala:45) 
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:245) 
    at scala.collection.AbstractTraversable.map(Traversable.scala:104) 
    ... 43 elided 

Answer 1

好了，我不知道要如何治療對象，而「TOTO」鍵，但也許你可以試試是這樣的：

val jsonValues = json.as[JsArray].value 

jsonValues.map(_.transform(transformer)).zip(jsonValues).foldLeft(JsArray()) 
{ 
    case (array, (transformResult, originalObject)) => 
    transformResult match { 
     case JsSuccess(newValue, _) => array :+ newValue 
     case err: JsError   => array :+ originalObject 
    } 
} 

結果是：

play.api.libs.json.JsArray = [{"toto":3},{"toto":3},{"tata":2}]