Filtering an xml file for certain elements and then removing unwanted nodes

scala-xml-filter.scala

import scala.xml._
import scala.xml.transform._

object Main extends App {

	import Stuff._

	val sourceXml = XML.loadFile("metadata.switchaai.xml")

	val allEntities = sourceXml \\ "EntityDescriptor"

	val wantedEntities = allEntities filter entitiesWeWant

	val strippedEntities = wantedEntities flatMap removeExtensions

	strippedEntities foreach printEntityToFile
}

object Stuff{

	private val wantedEntityNames = Seq("https://aai.unifr.ch/idp/shibboleth", "https://aai.unil.ch/idp/shibboleth")

	def entitiesWeWant(x: Node) = wantedEntityNames.contains((x \ "@entityID").text)

	def removeExtensions(x: Node) = new RuleTransformer(removeIt).transform(x)

	private def filenameFromEntity(x: Node) = {
		val entityName = (x \ "@entityID").text
		entityName.replace("https://", "").replace("/idp/shibboleth", "") + ".xml"
	}

	def printEntityToFile(x: Node) = {
		printToFile(new java.io.File(filenameFromEntity(x)))(p => {
  			p.println("""<?xml version="1.0" encoding="UTF-8"?>""" + x)
		})
	}

	private def printToFile(f: java.io.File)(op: java.io.PrintWriter => Unit) {
  		val p = new java.io.PrintWriter(f)
  		try { op(p) } finally { p.close() }
	}

	private val removeIt = new RewriteRule {
		override def transform(n: Node): NodeSeq = n match {
			case e: Elem if e.label == "Extensions" => NodeSeq.Empty
			case n => n
		}
	}	
}

Source XML file: http://metadata.aai.switch.ch/metadata.switchaai.xml

The aim of this was to only retrieve elements within the XML with a certain attribute value. Within that we need to remove a particular node.