Write JSon deserialiser (Read[T]) for play 2.1.x

Question

播放文档具有以下示例，用于为案例类创建读取[t]。它返回t或抛出异常。

在2.1.x中，建议返回jsresult [t]。它应该有t或所有错误。还建议使用JSPATH。我无法为2.1.x。

编写读取代码

这是play文档中的2.0.x代码

case class Creature(
  name: String, 
  isDead: Boolean, 
  weight: Float
)
In Play2.0.x, you would write your reader as following:
import play.api.libs.json._
implicit val creatureReads = new Reads[Creature] {
  def reads(js: JsValue): Creature = {
    Creature(
      (js  "name").as[String],
      (js  "isDead").as[Boolean],
      (js  "weight").as[Float]
    )
  }
}

对于2.1.x，我想我必须做

之类的事情

   implicit val creatureReads = new Reads[Creature] {
      def reads(js: JsValue): JsResult[Creature] = {
      (JsPath  "key1").read[String] 
/* at this point, I should either have key1's value or some error. I am clueless how to distinguish between the two and keep processing the rest of the JSon, accumulating all values or errors.*/
    }
}

Answer 1

说明在文档中：https://www.playframework.com/documentation/2.2.1/scalajsoncombinatorshttp://mandubian.com/2012/09/08/unveiling-play-2-dot-1-json-api-part1-part1-jspath-reads-combinators/

所以您在2.1中读到可以写为

implicit val creatureReads: Reads[Creature] = (
  (__  "name").read[String] and
  (__  "isDead").read[Boolean] and
  (__  "weight").read[Float]
)(Creature)