I was doing a little work in a project that spans a rather broad spectrum of the technology scale. One application in Groovy, the other is a Grails app, while another piece is ColdFusion. Overall a very interesting project.
One of the things I was working on is a sort of RESTful API, which is the portion written in Grails, and I found myself needing to craft an XML response that is essentially a domain-class transformed. I found this exercise in Grails to be quite simple.
Groovy provides a class called groovy.xml.MarkupBuilder. This class provides a DSL, or Domain Specific Language, for creating XML. The syntax is actually quite easy and takes very little practice to become natural. For the sake of demonstration let’s pretend I have a Person domain class, and I get a list of all the records from the database. With this list of persons I want to build an XML file that looks like this.
<people>
<person id='1'>
<firstname>Imogene</firstName>
<lastname>Coffey</lastName>
<email>nec.tempus.scelerisque@montesnascetur.ca</email>
</person>
<person id='2'>
<firstname>Marsden</firstName>
<lastname>Mcbride</lastName>
<email>malesuada.malesuada.Integer@vitae.ca</email>
</person>
<person id='3'>
<firstname>Jescie</firstName>
<lastname>Vang</lastName>
<email>neque.venenatis@ipsum.edu</email>
</person>
<person id='4'>
<firstname>August</firstName>
<lastname>Hewitt</lastName>
<email>Nullam@MorbimetusVivamus.org</email>
</person>
<person id='5'>
<firstname>Raven</firstName>
<lastname>Gilmore</lastName>
<email>Sed@mollisInteger.org</email>
</person>
</people>A pretty simple XML structure, but what does the domain class look like?
package com.adampresley.groovy
class Person {
String firstName
String lastName
String email = ""
static constraints = {
firstName(blank: false)
lastName(blank: false)
}
@Override
public String toString() {
"${firstName} ${lastName}"
}
}So with that class, and an understanding of how I wanted the XML to look, here’s how to use the MarkupBuilder class to achieve this.
package com.adampresley.groovy
import groovy.xml.MarkupBuilder
class TransformationsController {
def xml = {
def persons = Person.list()
def writer = new StringWriter()
def builder = new MarkupBuilder(writer)
builder.people {
persons.each { item ->
builder.person(id: item.id) {
firstName(item.firstName)
lastName(item.lastName)
email(item.email)
}
}
}
[ personXml: writer.toString() ]
}
}Cheers and happy coding!