JAX WS, JAXB and Null elements with attributes - attributes

Question

I am trying to consume a web service using JAXWS and wsimport. The WSIMPORT tool generated all the required classes and I can invoke the service without any issues.
However, I noticed in cases where response contains a nil element with valid attribute values, JAXWS fails to unmarshall it and throws a NullPointerException. I used SOAP UI to help debug and here's what I found. The response returns the following XML (Excerpt):
<externalIdentifiers>
<identifierType code="2" name="Passport" xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
<identifierValue/>
<issuingCountry xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
</externalIdentifiers>
In my Java code, when trying to read the "name" property of identifier type as above, it throws a NPE:
if(id.getIdentifierType() == null)
{
System.out.println("NULL");
}
System.out.println("Identifier Type: " + id.getIdentifierType().getName());
Output:
NULL
Exception in thread "main" java.lang.NullPointerException
To me that does looks a reasonable response as in the response, identifierType is set as xsi:nil="true". That is also perfectly valid XML as per W3C. Question is, how do I read the attribute values such as code and name in such a case?

Answer 1

Below is how you can support this use case:
Java Model
ExternalIdentifiers
You can change the identifierType property to be of type JAXBElement<IdentifierType> instead of IdentifierType. To do this you will need to annotate the property with #XmlElementRef.
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
#XmlRootElement
#XmlAccessorType(XmlAccessType.FIELD)
public class ExternalIdentifiers {
#XmlElementRef(name="identifierType")
private JAXBElement<IdentifierType> identifierType;
public JAXBElement<IdentifierType> getIdentifierType() {
return identifierType;
}
}
ObjectFactory
You will need a corresponding #XmlElementDecl annotation on a create method in a class annotated with #XmlRegistry.
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.namespace.QName;
#XmlRegistry
public class ObjectFactory {
#XmlElementDecl(name="identifierType")
public JAXBElement<IdentifierType> createIdentifierType(IdentifierType identifierType) {
return new JAXBElement(new QName("identifierType"), IdentifierType.class, identifierType);
}
}
Demo Code
input.xml
<?xml version="1.0" encoding="UTF-8"?>
<externalIdentifiers>
<identifierType code="2" name="Passport" xsi:nil="true"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" />
</externalIdentifiers>
Demo
import java.io.File;
import javax.xml.bind.*;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(ExternalIdentifiers.class, ObjectFactory.class);
Unmarshaller unmarshaller = jc.createUnmarshaller();
File xml = new File("src/forum18834036/input.xml");
ExternalIdentifiers externalIdentifiers = (ExternalIdentifiers) unmarshaller.unmarshal(xml);
System.out.println(externalIdentifiers.getIdentifierType().getValue().getName());
}
}
Output
Passport
Note
Currently there is a bug in EclipseLink JAXB (MOXy) regarding this use case:
http://bugs.eclipse.org/404944