Question

Is it possible, using JAXB, probably using MOXy, to “flatten” a base class into its subclass in marshalling, so that the Java inheritance is not visible in the XML? We have many hand-created classes that are based 1-to-1 on generated classes – the base class has no value in the XML.

If it isn’t obvious, we’re using the schemagen feature – starting with the Java, creating a schema.

Answer 1

You can mark the base class with @XmlTransient.

@XmlTransient
public class Root {
}

This will cause the Child class to ignore the inheritance (WRT JAXB):

public class Child extends Root {
}

For other examples see:

• How can I ignore a superclass?

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Follow Up Issue

The issue you posted on the forum is a bug. You can workaround it using a binding file like the following:

binding-a.xml

In the binding file specify a type name for the transient class. This type will not appear in the generated XML schema:

<?xml version="1.0" encoding="UTF-8"?>
<xml-bindings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="example.a">
    <java-types>
        <java-type name="MyOwnGrandpa" xml-transient="true">
            <xml-type name="MyOwnGrandpa2"/>
        </java-type>
    </java-types>
</xml-bindings>

example.a.MyOwnGrandpa

package example.a;

public class MyOwnGrandpa {

}

example.b.MyOwnGrandpa

package example.b;

public class MyOwnGrandpa extends example.a.MyOwnGrandpa {

}

example.Demo

package example;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.SchemaOutputResolver;
import javax.xml.transform.Result;
import javax.xml.transform.stream.StreamResult;

import org.eclipse.persistence.jaxb.JAXBContextFactory;

import example.b.MyOwnGrandpa;

public class Demo {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(1);
        properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, new File("src/exanmple/a/binding-a.xml"));
        JAXBContext jc = JAXBContext.newInstance(new Class[] {MyOwnGrandpa.class} , properties);
        jc.generateSchema(new MySOR());
    }

    private static class MySOR extends SchemaOutputResolver {

        @Override
        public Result createOutput(String arg0, String arg1) throws IOException {
            StreamResult result = new StreamResult(System.out);
            result.setSystemId(arg1);
            return result;
        }
    }

}

Generated Schema

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <xsd:complexType name="myOwnGrandpa"/>
</xsd:schema>

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UPDATE

This issue is also being discussed on the EclipseLink Forum:

• http://www.eclipse.org/forums/index.php?t=msg&th=208228&start=0&S=1ec5df3961f963fbc272ab4d94c9c70e