How do I bind XPath expression values to a template using Groovy - templates

Question

I have a small Groovy Class called "zzz". The purpose of this class is to first demonstrate successfully passing a binding to the template engine producing an output and then failing to bind to another template engine using what appears to be the same set of bindings.
V1.template contains the base message that will be used with the bindings to produce a final output. V1.properties contains an XPath expression that should grab the value from an XML document and add it to the bindings. T1.xml is the raw xml input file.
In the zzz Groovy Class I have hard coded the LastName in bindings1 and that works. But, when I grab the lastName value from the XML file and add it to bindings2 it fails. Both bindings appear to have exactly the same text, but I have noticed that bindings1 is of type Bindings and binding2 is of type Reference.
I assume that bindings2 being of Reference is what is causing my problem, but I don't know how to cast or convert it to Binding. Please let me know what I'm doing wrong.
I'm using Java 1.8 with groovy-all-2.3.10.jar
zzz.groovy:
import java.io.File;
import javax.xml.xpath.*
import javax.xml.parsers.DocumentBuilderFactory
class zzz {
def xpath
def records
def loadDocToCheck(File docToCheck) {
xpath = XPathFactory.newInstance().newXPath()
def builder = DocumentBuilderFactory.newInstance().newDocumentBuilder()
def inputStream = new FileInputStream( docToCheck )
records = builder.parse(inputStream).documentElement
}
def validateXpath(String xpathQuery ) {
def nodes = xpath.evaluate( xpathQuery, records, XPathConstants.NODESET )
nodes.collect { node -> node.textContent }
def nodeCount = 0
nodes.each { nodeCount++ }
nodeCount
}
def getXpath(String xpathQuery ) {
String retVal = ""
def nodes = xpath.evaluate( xpathQuery, records, XPathConstants.NODESET )
nodes.collect { node ->
retVal += node.getTextContent()
}
(retVal)
}
static main(args) {
def zzz = new zzz()
def testFile = new File("T1.xml")
zzz.loadDocToCheck(testFile)
def config = new ConfigSlurper().parse(new File("V1.properties").toURI().toURL())
String testFileNameOnly = testFile.getName()-testFile.getParent()
def bindings1 = [
"InputFile" : "$testFileNameOnly",
"LastName" : "Smith"
]
def templateFile1 = new File('V1.template')
println "templateFile1=${templateFile1.getAbsolutePath()}"
def engine1 = new groovy.text.GStringTemplateEngine()
def template1 = engine1.createTemplate(templateFile1).make(bindings1)
println template1.toString()
println "******************************"
def bindings2 = [:]
bindings2 << ["InputFile":"$testFileNameOnly"]
config.params.each { paramName, param ->
bindings2 << ["$paramName" : "${zzz.getXpath(param)}"]
}
println "bindings2=$bindings2"
def templateFile2 = new File('V1.template')
println "templateFile=${templateFile2.getAbsolutePath()}"
def engine2 = new groovy.text.GStringTemplateEngine()
def template2 = engine2.createTemplate(templateFile2).make(bindings2)
println template2.toString()
}
}
T1.xml:
<?xml version="1.0"?>
<MyRoot specVersion="3.03">
<employee>
<lastName>Smith</lastName>
<firstName>John</firstName>
</employee>
</MyRoot>
V1.template:
Input file: ${InputFile}
LastName: ${LastName}
V1.properties:
params {
LastName = '//MyRoot/employee/lastName/text()'
}

Answer 1

I found why the second template would could execute. The bindings must be in the form of Map, but I was passing in a GString as the key for the map. Note: "$parameterName" is a GString. After converting the key to a String the second template executed correctly.