How to convert a JsArray to sequence of case classes with spray-json?

问题

I have a a variable

var movieArray = movieText.parseJson

which is of class

println(movieArray.getClass)
class spray.json.JsArray

How do I convert it to a Sequence of case classes e.g

case class Movie(id: Int, title: String)

I tried

1. movieArray.convertTo[Seq[Movie]]
2. movieArray.map(_.convertTo[Movie])
3. for (i <- movieArray) println(i)

gives errors...

1. Cannot find JsonReader or JsonFormat type class for Seq[Movie]
2. value map is not a member of spray.json.JsValue
3. value foreach is not a member of spray.json.JsValue

Any suggestions? Help appreciated.

Correct answer https://github.com/spray/spray-json/issues/259

import spray.json._
import DefaultJsonProtocol._

var movieArray = movieText.stripMargin.parseJson

case class Movie(id: Int, title: String)

implicit val movieFormat = jsonFormat2(Movie)

movieArray.convertTo[Seq[Movie]]

回答1:

Each element of movieArray will have to be converted to an object of type Movie.

movieArray.map(_.convertTo[Movie])

Of course, the above statement depends on availability of logic to convert from Json to instance of Movie (JsonProtocol). Please refer the following for example

https://github.com/spray/spray-json#providing-jsonformats-for-case-classes

来源：https://stackoverflow.com/questions/50319629/how-to-convert-a-jsarray-to-sequence-of-case-classes-with-spray-json