Xml to json conversion with sibling elements with the same tag

[heitorbarbieri]

json4s version

4.1.0-M2

scala version

2.13.11

jdk version

openjdk version "11.0.18" 2023-01-17

scenario

import org.json4s.Xml.toJson
import org.json4s.native.JsonMethods.render
import org.json4s.native.Printer.compact
import javax.xml.parsers.{SAXParser, SAXParserFactory}
import scala.xml.Elem

object Xml2Json extends App {
  val xml = """<?xml version="1.0" encoding="UTF-8"?>
              |<book>
              |   <title>Some title</title>
              |   <description>some description</description>
              |   <author>
              |      <id>1</id>
              |      <name>some author name</name>
              |   </author>
              |   <review>nice book</review>
              |   <review>this book sucks</review>
              |   <review>amazing work</review>
              |</book>""".stripMargin

  val factory: SAXParserFactory = javax.xml.parsers.SAXParserFactory.newInstance()
  val parser: SAXParser = factory.newSAXParser()
  val elem: Elem = scala.xml.XML.withSAXParser(parser).loadString(xml)
  val json: JObject = toJson(elem).asInstanceOf[JObject]
  val jsonStr: String = compact(render(json))

  println(jsonStr)
}

output

{"book":{"title":"Some title","description":"some description","author":{"id":"1","name":"some author name"},"review":"nice book","review":"this book sucks","review":"amazing work"}}

expected output

{"book":{"title":"Some title","description":"some description","author":{"id":"1","name":"some author name"},"review": ["nice book", "this book sucks", "amazing work"]}}

reason

RFC 7159 says:

When the names within an object are not unique, the behavior of software that receives such an object is unpredictable. Many implementations report the last name/value pair only. Other implementations report an error or fail to parse the object, and some implementations report all of the name/value pairs, including duplicates.