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EclipseLink/DesignDocs/406697

Document History

  • April 26, 2013 - Initial Draft
  • May 17, 2013 - Updated after initial checkin

Requirements

Example

@XmlRootElement
public class Root {
 
	public String name;
 
	@XmlVariableNode("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 value() default "##default";
 
    Class type() default DEFAULT.class;   
 
    static final class DEFAULT {}
 
    boolean attribute() default false;
}

External Bindings

     <xs:element name="xml-variable-node" 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-element-wrapper" minOccurs="0"/>
                        <xs:element ref="xml-properties" minOccurs="0" />
                    </xs:all>
                    <xs:attribute name="xml-path" type="xs:string" />
                    <xs:attribute name="read-only" type="xs:boolean" default="false" />
                    <xs:attribute name="write-only" type="xs:boolean" default="false" />
                    <xs:attribute name="container-type" type="xs:string" default="##default" />
                    <xs:attribute name="type" type="xs:string" default="##default" />
                    <xs:attribute name="isAttribute" type="xs:boolean" default="false" />
                    <xs:attribute name="java-variable-attribute" type="xs:string"  />
                    <xs:attribute name="nillable" type="xs:boolean" default="false" />
                    <xs:attribute name="required" type="xs:boolean" default="false" />
                </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.xmlvariablenode.RootNoAnnotations">
            <xml-root-element name="root" />
            <java-attributes>
                <xml-variable-node java-attribute="things" java-variable-attribute="thingName"/>
            </java-attributes>
		</java-type>
	</java-types>
</xml-bindings>

Design

2 new mappings will be created XMLVariableXPathObjectMapping and XMLVariableXPathCollectionMapping it will extend the CompositeMappings

The Annotation will be allowed on Single objects as well as lists or maps and can be used in conjunction with several other annotations like XmlElementWrapper, Xpath and XmlJavaTypeAdapter. When used with an adapter the variable attribute must exist on the adapted type.

For Schema generation when this is present an xs:any will be added to the xsd

Exception Cases

  • 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.
  • The variable attribute can only be a simple thing - String, QName or Number type
  • The value of the variable attribute can not be null - exception will be thrown

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>
  • don`t write out that property itself as nested if it is the variable field - currently need to mark that property as transient.
  • in conjunction with adapters?
  • elementwrapper
  • schemagen
  • Binder
  • isnil nullpolicy
  • map
  • map <a,b> doesn't automatically pull in B