Question

我正在尝试编写一个函数来编写可能具有Infinity值的双精度（在JSON中不存在）。

以下是我想要实现的一些例子：

OpenQuery

到目前为止，我已经创建了一个增强的JsPath类，并添加了名为Input: Double.PositiveInfinity Output: { "positiveInfinty": true, "negativeInfinty": false, "value": null } Input: 12.3 Output: { "positiveInfinty": false, "negativeInfinty": false, "value": 12.3 }的函数：

writeInfinite

代码全部编译，这是我正在使用的测试：

case class EnhancedJsPath(jsPath: JsPath) {

    private def infinityObject(pos: Boolean, neg: Boolean, value: Option[Double]): JsObject = Json.obj(
        "positiveInfinity" -> pos,
        "negativeInfinity" -> neg,
        "value" -> value
    )

    def writeInfinite: OWrites[Double] = OWrites[Double] { d =>
        if (d == Double.PositiveInfinity) { infinityObject(true, false, None) }
        else if (d == Double.NegativeInfinity) { infinityObject(false, true, None) }
        else { infinityObject(false, false, Some(d)) }
    }
}

object EnhancedJsPath {
    implicit def jsPathToEnhancedJsPath(jsPath: JsPath): EnhancedJsPath = EnhancedJsPath(jsPath)
}

测试失败，因为case class Dummy(id: String, value: Double) object Dummy { implicit val writes: Writes[Dummy] = ( (JsPath \ "id").write[String] and (JsPath \ "value").writeInfinite )(unlift(Dummy.unapply)) } test("EnhancedJsPath.writesInfinite should set positive infinity property") { val d = Dummy("123", Double.PositiveInfinity, Some(Double.PositiveInfinity)) val result = Json.toJson(d) val expected = Json.obj( "id" -> "123", "value" -> Json.obj( "positiveInfinity" -> true, "negativeInfinity" -> false, "value" -> JsNull ) ) assert(result == expected) }的值为：

result

而不是：

{
    "id": "123",
    "positiveInfinity": true,
    "negativeInfinity": false,
    "value": null
}

我无法弄清楚如何修改我的{ "id": "123", "value": { "positiveInfinity": true, "negativeInfinity": false, "value": null } }以尊重路径。

Answer 1

查看JsPath#write[A]或JsPath#writeNullable[A]有助于：

def write[T](implicit w: Writes[T]): OWrites[T] = Writes.at[T](this)(w)

Writes.at接受JsPath，这就是write和writeNullable保留所调用路径的方式。您需要做的就是用writeInfinite包装当前的jsPath实现，并传递def writeInfinite: OWrites[Double] = Writes.at(jsPath)(OWrites[Double] { d => if (d == Double.PositiveInfinity) infinityObject(true, false, None) else if (d == Double.NegativeInfinity) infinityObject(false, true, None) else infinityObject(false, false, Some(d)) })值：

scala> Json.toJson(d)
res5: play.api.libs.json.JsValue = {"id":"123","value":{"positiveInfinity":true,"negativeInfinity":false,"value":null}}

它有效：

appendChild

播放JsPath为Infinite Double写道

1 个答案: