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Difference between revisions of "EclipseLink/DesignDocs/317962/Phase2.1"

(→‎XML Schema)
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</xs:complexType>
 
</xs:complexType>
 
</source>
 
</source>
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An unbounded element ref to the new global <code>xml-property</code> element will be added to:
+
An <code>xml-properties</code> element will be used to wrap an unbounded element ref to the new global <code>xml-property</code> element. This structure will look like:
 +
<source lang="xml">
 +
<xs:element name="xml-properties" minOccurs="0">
 +
    <xs:complexType>
 +
        <xs:sequence>
 +
            <xs:element ref="xml-property" minOccurs="0" maxOccurs="unbounded" />
 +
        </xs:sequence>
 +
    </xs:complexType>
 +
</xs:element>
 +
</source>
 +
This structure will be added to:
 
*java-type
 
*java-type
 
*xml-any-attribute
 
*xml-any-attribute

Revision as of 15:01, 29 July 2010

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-property XmlProperty X X X
xml-transformation XmlTransformation X X
xml-read-transformer XmlReadTransformer X X
xml-write-transformer XmlWriteTransformer X X
xml-class-extractor XmlClassExtractor X

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" default="java.lang.String" />
</xs:complexType>

An xml-properties element will be used to wrap an unbounded element ref to the new global xml-property element. This structure will look like: 

<xs:element name="xml-properties" minOccurs="0">
    <xs:complexType>
        <xs:sequence>
            <xs:element ref="xml-property" minOccurs="0" maxOccurs="unbounded" />
        </xs:sequence>
    </xs:complexType>
</xs:element>

This structure 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-access-methods" type="xml-access-methods" minOccurs="0"/>
                    <!-- 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-read-transformer">
                        <xs:complexType>
                            <xs:attribute name="method" type="xs:string" />
                            <xs:attribute name="transformer-class" type="xs:string" />
                        </xs:complexType>
                    </xs:element>
                    <xs:element name="xml-write-transformer" minOccurs="0" maxOccurs="unbounded">
                        <xs:complexType>
                            <xs:attribute name="method" type="xs:string" />
                            <xs:attribute name="xml-path" type="xs:string" />
                            <xs:attribute name="transformer-class" type="xs:string" />
                        </xs:complexType>
                    </xs:element>
                </xs:all>
                <xs:attribute name="attribute-type" type="xs:string" />
                <!-- xs:attribute name="fetch" type="orm:fetch-type"/ -->
                <xs:attribute name="mutable" type="xs:boolean" default="false"/>
                <xs:attribute name="name" type="xs:string" use="required"/>
                <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: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>

xml-class-extractor

Purpose

The xml-class-extractor element provides a means for 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 - a global element/complex type pair will be added, and a ref will be added to java-type: 

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

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.Person">
    <xml-class-extractor class="org.example.MyClassExtractor" />
</java-type>
org.example.Person.java
package org.example;
 
class Person {
    String name;
}
org.example.Employee.java
package org.example;
 
class Employee extends Person {
    String id;
}
org.example.MyClassExtractor.java
package org.example;
 
class MyClassExtractor extends org.eclipse.persistence.descriptors.ClassExtractor {
    /**
     * This method simply returns Employee.class.  Typically, the class to be 
     * returned would be based on the given Record.
     */
    public static Class extractClassFromRow(Record databaseRow, Session session) {
        return Employee.class;
    }
}

Decisions

This section lists decisions made. These are intended to document the resolution of open issues or constraints added to the project that are important.

Issue# Description/Notes Decision
1 xml-class-extraction-method We will not provide support for setting a class extraction method name on the InheritancePolicy. Please refer to this bug for additional information.
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