EclipseLink/DesignDocs/406697

Document History

• April 26, 2013 - Initial Draft

Requirements

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

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"}
}}

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;    
 
    String getMethod() default "##default";
 
    String setMethod() default "##default";
 
    static final class DEFAULT {}
}

External Bindings

     <xs:element name="xml-variable-element" substitutionGroup="java-attribute">
        <xs:complexType>
            <xs:complexContent>
                <xs:extension base="java-attribute">
                    <xs:all>
                        <xs:element ref="xml-access-methods" minOccurs="0" />
                        <xs:element ref="xml-java-type-adapter" minOccurs="0"/>
                        <xs:element ref="xml-properties" minOccurs="0" />
                        <xs:element ref="xml-element-refs" minOccurs="0" />
                    </xs:all>
                    <xs:attribute name="xml-mixed" type="xs:boolean" default="false" />
                    <xs:attribute name="lax" type="xs:boolean" default="false" />
                    <xs:attribute name="dom-handler" type="xs:string" default="javax.xml.bind.annotation.W3CDomHandler" />
                    <xs:attribute name="read-only" type="xs:boolean" default="false" />
                    <xs:attribute name="write-only" type="xs:boolean" default="false" />
                    <xs:attribute name="xml-path" type="xs:string" />
                    <xs:attribute name="container-type" type="xs:string" default="##default" />
                    <xs:attribute name="type" type="xs:string" default="##default" />
		    <xs:attribute name="java-attribute" type="xs:string"  />
                </xs:extension>
            </xs:complexContent>
        </xs:complexType>
    </xs:element>

 <?xml version="1.0" encoding="US-ASCII"?>
<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm">
	<java-types>
		<java-type name="org.eclipse.persistence.testing.jaxb.xmlvariableelement.RootNoAnnotations">
            <java-attributes>
                <xml-variable-element java-attribute="things" java-variable-attribute="thingName">
                    <!--xml-java-type-adapter value="org.eclipse.persistence.testing.jaxb.externalizedmetadata.xmlanyelement.MyDomAdapter" /-->
                </xml-variable-element>
            </java-attributes>
		</java-type>
	</java-types>
</xml-bindings>

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. Potential future considerations would be to allow multiple XmlVariableNode annotations on the same object with some type of regular expression/pattern to differentiate them.

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
• in conjunction with adapters?
• elementwrapper
• schemagen
• Binder
• isnil nullpolicy
• map
• map <a,b> doesn't automatically pull in B