玩框架JSON转换器，如何使用递归路径(jsPath)

Question

假设我有一个JSON:

{
  "name" : "Watership Down",
  "location" : {
    "lat" : 51.235685,
    "long" : -1.309197
  },
  "residents" : [ {
    "name" : "Fiver",
    "age" : 4,
    "role" : null
  }, {
    "name" : "Bigwig",
    "age" : 6,
    "role" : "Owsla"
  } ]
}

如果我这样做

val transformer1 = (__  'name).json.update(of[JsValue].map(a => JsString("x")))

将name字段更改为"x"，工作正常。

但是如果我想递归地将所有名称更改为"x"，我认为我可以使用递归jsPath，像这样:

val transformerRecursive = (__ \ 'name).json.update(of[JsValue].map(a => JsString("x")))

但是当我尝试时，我得到这个错误:

scala

> jsobject.transform (transformerRecursive)res1: play.api.libs.json.JsResult [play.api.libs.json。JsObject] = JsError(List(//name,List(ValidationError(List(error.path.result.multiple)，WrappedArray())))))

)

我应该如何使用递归路径与JSON转换器在游戏框架?

Answer 1

正如@irundaia所说，您需要遍历数组并更新每个值(为此使用Reads.list):

val t = (__  "residents").json.update(
  Reads.list(
    (__  "name").json.update(
      Reads.pure(JsString("x"))
    )
  ).map(JsArray)
)
scala> res1: play.api.libs.json.JsResult[play.api.libs.json.JsObject] = JsSuccess({"name":"Watership Down","location":{"lat":51.235685,"long":-1.309197},"residents":[{"name":"x","age":4,"role":null},{"name":"x","age":6,"role":"Owsla"}]},/residents)

Answer 2

感谢@andrey。女士，我设法解决了我的问题，我想清空一个嵌套的JsArray。以下是如何做到这一点的示例，仅供任何可能找到任何帮助的人使用:

import play.api.libs.json._
case class D(yay: String, nay: String)
case class C(ds: Seq[D], baz: Boolean)
case class B(cs: Seq[C], bar: Int)
case class A(b: B, foo: String)
implicit val formatD: OFormat[D] = Json.format
implicit val formatC: OFormat[C] = Json.format
implicit val formatB: OFormat[B] = Json.format
implicit val formatA: OFormat[A] = Json.format
val foo = A(
  B(Seq(C(Seq(D("foo", "bar")), true), C(Seq(D("oof", "rab")), false)), 42),
  "test"
)
val dsIgnoringReads =
  (__  "b"  "cs").json.update(Reads.seq((__  "ds").json.update(Reads.pure(JsArray()))).map(JsArray))
dsIgnoringReads.reads(Json.toJson(foo)).get

这生产

res0: play.api.libs.json.JsObject = 
  {"b":{"cs":[{"ds":[],"baz":true},{"ds":[],"baz":false}],"bar":42},"foo":"test"}