EclipseLink/DesignDocs/317962/Phase2.1

Phase 2.1 - Additional MOXy external metadata support

This phase of development involves providing additional MOXy external metadata support that will allow configuration similar to that of deployment XML

Xml Metadata Tags

The following Xml metadata tags will be targeted in this phase:

XML Metadata Tag	MOXy Annotation	Package	Type	Field	Method
xml-class-extractor	XmlClassExtractor		X

xml-class-extractor

Purpose

The xml-class-extractor element allows complex inheritance support. A class extractor is registered with the descriptor to override the default inheritance mechanism. This allows for a user defined class indicator in place of providing an explicit class indicator field. The instance registered must extend the org.eclipse.persistence.descriptors.ClassExtractor class and implement the extractClassFromRow(Record, Session) method; this method is used to determine which class to instantiate when unmarshalling.

XML Schema

Following is the proposed schema structure for xml-class-extractor - it will be added to java-type:

<xs:element name="xml-class-extractor">
    <xs:complexType>
        <xs:attribute name="class" type="xs:string" use="required"/>
    </xs:complexType>
</xs:element>

Example

The following example will demonstrate how the xml-class-extractor can be applied.

Setting xml-class-extractor via EclipseLink XML metadata can be accomplished as follows:

<java-type name="org.example.Employee">
    <xml-class-extractor class="org.example.MyClassExtractor" />
</java-type>

xml-property

Purpose

The xml-property element provides a means to set a property on a mapping or descriptor.

XML Schema

Following are the proposed schema structures for xml-property:

<xs:element name="xml-property" type="xml-property" />
<xs:complexType name="xml-property">
    <xs:attribute name="name" type="xs:string" use="required" />
    <xs:attribute name="value" type="xs:string" use="required" />
    <xs:attribute name="value-type" type="xs:string" />
</xs:complexType>

An element ref to the new global xml-property element will be added to:

• java-type
• xml-any-attribute
• xml-attribute
• xml-any-element
• xml-element
• xml-elements
• xml-element-ref
• xml-element-refs
• xml-inverse-reference
• xml-value
• xml-transformation

Example: type-level xml-property

The following example will demonstrate how a type-level xml-property can be applied.

Setting xml-property on a type via EclipseLink XML metadata can be accomplished as follows:

<java-type name="org.example.Employee">
    <xml-property name="identifier" value="101" value-type="Integer.class" />
    <xml-property name="isTrue" value="false" value-type="Boolean.class" />
</java-type>

Example: property-level xml-property

The following example will demonstrate how a property-level xml-property can be applied.

Setting xml-property on a property via EclipseLink XML metadata can be accomplished as follows:

<java-type name="org.example.Employee">
    <java-attributes>
        <xml-element java-attribute="myelement">
            <xml-property name="isAttribute" value="false" value-type="Boolean.class" />
            <xml-property name="comment" value="this is an element" value-type="String.class" />
        </xml-element>
    </java-attributes>
</java-type>

xml-transformation

Purpose

The xml-transformation element is used to configure an org.eclipse.persistence.oxm.mappings.XMLTransformationMapping. Transformation mappings are used to create a custom mapping where one or more XML nodes can be used to create the object to be stored in a Java class's attribute.

XML Schema

Following is the proposed schema structure for xml-transformation:

<xs:element name="xml-transformation" substitutionGroup="java-attribute">
    <xs:complexType>
        <xs:complexContent>
            <xs:extension base="java-attribute">
                <xs:all>
                    <xs:element name="xml-read-transformer">
                        <xs:complexType>
                            <xs:attribute name="transformer-class" type="xs:string" />
                            <xs:attribute name="method" type="xs:string" />
                        </xs:complexType>
                    </xs:element>
                    <xs:element name="xml-write-transformer" minOccurs="0" maxOccurs="unbounded">
                        <xs:complexType>
                            <xs:attribute name="xml-path" type="xs:string" />
                            <xs:attribute name="transformer-class" type="xs:string" />
                            <xs:attribute name="method" type="xs:string" />
                        </xs:complexType>
                    </xs:element>
                    <!-- xs:element name="xml-accessor-type" type="xml-access-type" minOccurs="0"/ -->
                    <xs:element name="xml-property" type="xml-property" minOccurs="0" maxOccurs="unbounded"/>
                    <xs:element name="xml-access-methods" type="xml-access-methods" minOccurs="0"/>
                </xs:all>
                <xs:attribute name="name" type="xs:string" use="required"/>
                <!-- xs:attribute name="fetch" type="orm:fetch-type"/ -->
                <xs:attribute name="optional" type="xs:boolean" default="false"/>
                <xs:attribute name="xml-accessor-type" type="xml-access-type" minOccurs="0" default="PUBLIC_MEMBER"/>
                <xs:attribute name="mutable" type="xs:boolean" default="false"/>
                <xs:attribute name="attribute-type" type="xs:string" />
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>
</xs:element>

Example

The following example will demonstrate how xml-transformation can be applied.

Setting xml-transformation via EclipseLink XML metadata can be accomplished as follows:

<java-type name="org.example.Employee">
    <java-attributes>
        <xml-transformation java-attribute="hours" optional="true">
            <xml-read-transformer transformer-class="org.example.NormalHoursTransformer" />
            <xml-write-transformer xml-path="normal-hours/start-time/text()" transformer-class="org.example.StartTimeTransformer"/>
            <xml-write-transformer xml-path="normal-hours/end-time/text()" transformer-class="org.example.EndTimeTransformer"/>
            <xml-access-methods get-method="getNormalHours" set-method="setNormalHours" />
        </xml-transformation>
    </java-attributes>
</java-type>