EclipseLink/DesignDocs/406697

Document History

• April 26, 2013 - Initial Draft

Requirements

• Related Enhancement Request - bug 406697
  
• Required for JSON schema generation - JSON Schema Generation
  

API

The following annotation will be added
org.eclipse.persistence.oxm.annotations.XmlVariableNode

@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface XmlVariableNode {
    String attributeName();
 
    Class type() default DEFAULT.class;    
 
    static final class DEFAULT {}
}

Example

@XmlRootElement
public class Root {
 
	public String name;
 
	@XmlVariableNode(attributeName="thingName")
	public List<Thing> things;
}
 
public class Thing {
        @XmlTransient
	public String thingName;
	public String thingValue;
}

Root r = new Root();
r.name = "theRootName";
r.things = new ArrayList<Thing>();
Thing thing1 = new Thing();
thing1.thingName = "thinga";
thing1.thingValue = "thingavalue";
 
Thing thing2 = new Thing();
thing2.thingName = "thingb";
thing2.thingValue = "thingbvalue";
 
Thing thing3 = new Thing();
thing3.thingName = "thingc";
thing3.thingValue = "thingcvalue";
r.things.add(thing1);
r.things.add(thing2);
r.things.add(thing3);

marshaller.marshal(r, System.out)
XML
<root>
   <name>theRootName</name>
   <thinga>
       <thingValue>thingavalue</thingValue>
   </thinga>
   <thingb>
       <thingValue>thingbvalue</thingValue>
   </thingb>
   <thingc>
       <thingValue>thingcvalue</thingValue>
   </thingc>
</root>

marshaller.marshal(r, System.out)
JSON
{"root":{
   "name":"theRootName"
   "thinga":{
       "thingValue":"thingavalue"},   
   "thingb":{
       "thingValue":"thingbvalue"},
   "thingc":{
       "thingValue":"thingcvalue"}
}}

Design

A new mapping will be created XMLVariableXPathMapping and it will extend the AnyCollectionMapping

This mapping will assume that the key names are unique so will never write ['s in JSON

This annotation only makes sense when the referenced type is a complex thing. An exception will be thrown if this annotation is used on a simple object or List of simple things.

Limitations

Since this makes use of the any logic during unmarshal and MOXy only handles one Any mapping on a class if a class makes use of the XmlVariableNode annotation then that class can not have XmlAnyElement annotations or any other variables that would cause AnyObject or AnyCollection mappings to be created.

Note/Issues

• inheritance
• List<Object>
• single case ie:not on a collection XMLVariableXPathObjectMapping XMLVariableXPathCollectionMapping
• external bindings
• don`t write out that property itself as nested if it is the variable field - currently need to mark that property as transient.
• startcollection and endcollection [ ]'s in JSON
• could specify get/set method instead of attribute
• namespaces