在播放框架 JsObject 中解析 Json 数组

发布于02月26日

我有以下Json:

{
  "web-category" : "macaroons",
  "sub-categories" : [
     { "name" : "pink" },
     { "name" : "blue" },
     { "name" : "green" }
  ]

}

I have got it in Play as a JsObject. So I can now successfully do the following:

//(o is the JsObject)

val webCat:Option[String] = (o \ "web-category").asOpt[String]

println(webCat.toString)

>> Some(macaroons)

到目前为止，一切顺利.但是如何访问数组Json对象呢？我有这个...

val subCats:Option[JsArray] = (o \ "sub-categories").asOpt[JsArray]

println(subCats.toString)

>> Some([{"name" : "blue"},{"name" : "green"},{"name" : "pink"}])

but what I need is to take the JsArray and get a List of all the names something like this:

List("blue", "green", "pink")

不知道如何访问JsArray.

谢谢你在这方面的帮助.

推荐答案

I'd argue that it's generally a good idea to move from JSON-land to native-Scala-representation-land as early as possible. If obj is your JsObject, for example, you can write this:

val subCategories = (obj \ "sub-categories").as[List[Map[String, String]]]

val names = subCategories.map(_("name"))

Or even:

case class Category(name: String, subs: List[String])

import play.api.libs.functional.syntax._

implicit val categoryReader = (
  (__ \ "web-category").read[String] and
  (__ \ "sub-categories").read[List[Map[String, String]]].map(_.map(_("name")))
)(Category)

And then: