Object-XML Binding: How do I map from java to enumerated xml tags

Question

Hi. I'm new to Object-XML binding and toplink. XML that I'm trying to model in a schema has enumerated elements, e.g. </module_0></module_1><module_n> instead of many </module> elements. To simplify the schema I've opted to use </module> anyway with unbounded cardinality and imported this into a new project.
What I would like to know is if I can use Toplink to map the java object back to the enumerate element types and vice versa?
Thanks for your help.
GeePee

Answer 1

Hi Geepee,
Below is an approach you can use if you have a fixed number of moduleX elements. In the example below X=3.
Assume a 2 object model Root & Module, where Root has a list of Module instances:
@XmlRootElement(name="root")
public class Root {
    private List<Module> module = new ArrayList<Module>(3);
    ...// Accessors omitted
}It is currently not possible to map the items in the module list to the XML elements (module1-module3), but it would be possbile to map an object (see below) with 3 properties to those XML elements:
public class AdaptedModuleList {
    private Module module1;
    private Module module2;
    private Module module3;
    ...// Accessors omitted
}What is required is a means to convert the unmappable object to a mappable one. This is done using a Converter:
import org.eclipse.persistence.mappings.DatabaseMapping;
import org.eclipse.persistence.mappings.converters.Converter;
import org.eclipse.persistence.sessions.Session;
public class ModuleListConverter implements Converter {
    public void initialize(DatabaseMapping mapping, Session session) {}
    public Object convertDataValueToObjectValue(Object dataValue, Session session) {
        AdaptedModuleList adaptedModuleList = (AdaptedModuleList) dataValue;
        if(null == adaptedModuleList) {
            return null;
        List<Module> moduleList = new ArrayList<Module>(3);
        moduleList.add(adaptedModuleList.getModule1());
        moduleList.add(adaptedModuleList.getModule2());
        moduleList.add(adaptedModuleList.getModule3());
        return moduleList;
    public Object convertObjectValueToDataValue(Object objectValue, Session session) {
        List<Module> moduleList = (List<Module>) objectValue;
        if(null == moduleList) {
            return null;
        AdaptedModuleList adaptedModuleList = new AdaptedModuleList();
        int moduleListSize = moduleList.size();
        if(moduleListSize > 0) {
            adaptedModuleList.setModule1(moduleList.get(0));
        if(moduleListSize > 1) {
            adaptedModuleList.setModule2(moduleList.get(1));
        if(moduleListSize > 2) {
            adaptedModuleList.setModule3(moduleList.get(2));
        return adaptedModuleList;
    public boolean isMutable() {
        return true;
}The converter is added to the mapping metadata through the use of a Customizer:
import org.eclipse.persistence.config.DescriptorCustomizer;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.oxm.mappings.XMLCompositeCollectionMapping;
import org.eclipse.persistence.oxm.mappings.XMLCompositeObjectMapping;
public class RootCustomizer implements DescriptorCustomizer {
    public void customize(ClassDescriptor descriptor) throws Exception {
        XMLCompositeCollectionMapping originalModuleMapping = (XMLCompositeCollectionMapping) descriptor.removeMappingForAttributeName("module");
        XMLCompositeObjectMapping newModuleMapping = new XMLCompositeObjectMapping();
        newModuleMapping.setAttributeName(originalModuleMapping.getAttributeName());
        newModuleMapping.setXPath(".");
        newModuleMapping.setReferenceClass(AdaptedModuleList.class);
        newModuleMapping.setConverter(new ModuleListConverter());
        descriptor.addMapping(newModuleMapping);
}Part 1/2