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EclipseLink/DesignDocs/293925/MOXyExtensions/XMLDirectMapping

XMLDirectMapping

Requirements

Provide support for XML direct mapping configuration via XML metadata file.

The following structures are to be extended to support XML direct mapping configuration:


The following should be configurable:

Design

Basic XML direct mapping support

We will use the xml-attribute, xml-element and xml-value structures to support direct mappings. For example, the following XML metadata snippet would be used to setup a direct mapping for an empId attribute:

<xml-attribute java-attribute="empId" />

If empId was to be mapped to id, then the following would be used:

<xml-attribute java-attribute="empId" name="id" />

The same example mapped to an id element:

<xml-element java-attribute="empId" name="id" />

The same example mapped to a simple type:

<xml-value java-attribute="empId" />

Path-based mapping support

We will support path-based mappings on xml-attribute and xml-element via xml-path attribute. If xml-path is present, it is assumed to contain the entire XPath, hence the name and namespace attributes - if set - will be ignored, as well as any xml-element-wrapper declarations. Path-based mappings will not apply to xml-value. An example of configuring a path-based XML direct mapping can be found below, and additional information/examples here.

Positional Mappings

Positional mappings will be supported on xml-element. An example of configuring a positional XML direct mapping can be found below and additional information/examples here. Note that positional mappings cannot be applied to xml-attribute or xml-value.

Read Only

Read only will be supported via boolean attribute on xml-attribute, xml-element and xml-value. An example of configuring a read only XML direct mapping can be found below and here.

Write Only

Write only will be supported via boolean attribute on xml-attribute, xml-element and xml-value. An example of configuring a write only XML direct mapping can be found below and here.

CDATA

CDATA will be supported via boolean attribute on xml-element and xml-value. An example of configuring a XML direct mapping as CDATA can be found below and here. Note that CDATA cannot be applied to xml-attribute.

Null Poilcy

Null policy will be supported via sub-element on xml-attribute, xml-element and xml-value. The proposed schema modifications for the global null policy elements/complex types can be found here. An example of configuring a null policy on an XML direct mapping can be found below.

Get/Set Method Names

The get/set method names on xml-attribute, xml-element and xml-value will be configurable via sub-element. An example of configuring the accessor methods on a XML direct mapping can be found below, and additional examples and proposed schema changes can be found here.

Example: xml-attribute & xml-element

The following example will demonstrate how to configure XML direct mappings via XML metadata by using xml-attribute & xml-element.

org.example.Employee.java

package org.example;
 
public class Employee {
    public int empId;
    public int projectId;
    public String firstName;
    public String lastName;
    public String projectName;
    public String data1;
    public String data2;
    public double salary;
    public String privateData;
    public String characterData; 
    public String someString;
    public String aString;
 
    @javax.xml.bind.annotation.XmlTransient
    public boolean isSomeStringSet;
 
    String getProject() {
        return projectName; 
    }
 
    void setProject(String name) {
        projectName = name;
    }
 
    String getSomeString() { 
        return someString; 
    }
 
    void setSomeString(String str) {
        someString = str; 
    }
 
    public boolean isSetSomeString(Boolean ignoredParam) {
        return isSomeStringSet;
    }
 
    String getAString() { 
        return aString; 
    }
 
    void setAString(String str) {
        aString = str; 
    }
}

Deployment XML

<class-mapping-descriptor xsi:type="xml-class-mapping-descriptor">
    <alias>Employee</alias>
    <attribute-mappings>
        <attribute-mapping xsi:type="xml-direct-mapping">
           <attribute-name>empId</attribute-name>
           <field name="@id" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
           <attribute-name>firstName</attribute-name>
           <field name="info/personal-info/first-name/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
           <attribute-name>lastName</attribute-name>
           <field name="info/personal-info/last-name/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>mgrId</attribute-name>
            <field name="projects/prj:project/@prj:managerId" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
           <attribute-name>projectName</attribute-name>
           <get-method>getProject</get-method>
           <set-method>setProject</set-method>
           <field name="projects/prj:project/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>data1</attribute-name>
            <field name="pieces-of-data/data[1]/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>data2</attribute-name>
            <field name="pieces-of-data/data[2]/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>salary</attribute-name>
            <read-only>true</read-only>
            <field name="@salary" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>privateData</attribute-name>
            <field name="private-data/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>characterData</attribute-name>
            <field name="character-data/text()" xsi:type="node"/>
            <is-cdata>true</is-cdata>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>projectId</attribute-name>
            <field name="project-id/text()" xsi:type="node"/>
            <null-value xsi:type="xsd:int">-1</null-value>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>someString</attribute-name>
            <get-method>getSomeString</get-method>
            <set-method>setSomeString</set-method>
            <field name="some-string/text()" xsi:type="node"/>
            <null-policy xsi:type="null-policy">
                <null-representation-for-xml>EMPTY_NODE</null-representation-for-xml>
            </null-policy>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>aString</attribute-name>
            <get-method>getAString</get-method>
            <set-method>setAString</set-method>
            <field name="a-string/text()" xsi:type="node"/>
            <null-policy xsi:type="null-policy">
                <empty-node-represents-null>true</empty-node-represents-null>
                <null-representation-for-xml>ABSENT_NODE</null-representation-for-xml>
            </null-policy>
        </attribute-mapping>
    <attribute-mappings>
    <descriptor-type>aggregate</descriptor-type>
    <default-root-element>employee</default-root-element>
    <default-root-element-field name="employee" xsi:type="node"/>
    <namespace-resolver>
        <namespaces>
            <namespace>
                <prefix>prj</prefix>
                <namespace-uri>http://www.example.com/projects</namespace-uri>
            </namespace>
        </namespaces>
    </namespace-resolver>
</class-mapping-descriptor>

XML Instance Document (read)

<?xml version="1.0" encoding="UTF-8"?>
<ns0:employee id="66" salary="123456.78" xmlns:ns0="http://www.example.com/employees" xmlns:prj="http://www.example.com/projects" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <projects>
        <prj:project prj:managerId="99">XML External Metadata Support</prj:project>
    </projects>
    <info>
        <personal-info>
            <first-name>Joe</first-name>
            <last-name>Oracle</last-name>
        </personal-info>
    </info>
    <project-id/>
    <pieces-of-data>
        <data>data one</data>
        <data>data two</data>
        <data>data three</data>
    </pieces-of-data>
    <private-data>This is some private data</private-data>
    <character-data><![CDATA[<characters>a b c d e f g</characters>]]></character-data>
    <some-string />
</ns0:employee>

XML Instance Document (write)

<?xml version="1.0" encoding="UTF-8"?>
<ns0:employee id="66" xmlns:ns0="http://www.example.com/employees" xmlns:prj="http://www.example.com/projects" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <projects>
        <prj:project prj:managerId="99">XML External Metadata Support</prj:project>
    </projects>
    <project-id>999</project-id>
    <info>
        <personal-info>
            <first-name>Joe</first-name>
            <last-name>Oracle</last-name>
        </personal-info>
    </info>
    <pieces-of-data>
        <data>data one</data>
        <data>data two</data>
    </pieces-of-data>
    <private-data>This is some private data</private-data>
    <character-data><![CDATA[<characters>a b c d e f g</characters>]]></character-data>
    <some-string xsi:nil="true" />
    <a-string/>
</ns0:employee>

org/example/eclipselink-oxm.xml

This XML file demonstrates configuring XML direct mappings on the "org.example.Employee" class.

<?xml version="1.0" encoding="US-ASCII"?>
<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xml-schema namespace="http://www.example.com/employees">
        <xml-ns namespace-uri="http://www.example.com/projects" prefix="prj"/>
    </xml-schema>
    <java-types>
        <java-type name="org.example.Employee" xml-accessor-type="FIELD">
            <xml-root-element name="employee" />
            <java-attributes>
                <xml-attribute java-attribute="empId" xml-path="@id" />
                <xml-attribute java-attribute="salary" read-only="true" />
                <xml-attribute java-attribute="mgrId" xml-path="projects/prj:project/@prj:managerId" />
                <xml-element java-attribute="firstName" xml-path="info/personal-info/first-name/text()" />
                <xml-element java-attribute="lastName" xml-path="info/personal-info/last-name/text()" />
                <xml-element java-attribute="data2" xml-path="pieces-of-data/data[2]/text()" />
                <xml-element java-attribute="data1" xml-path="pieces-of-data/data[1]/text()" />
                <xml-element java-attribute="privateData" name="private-data" write-only="true" />
                <xml-element java-attribute="characterData" name="character-data" cdata="true" />
                <xml-element java-attribute="projectId" name="project-id" default-value="-1" />
                <xml-element java-attribute="projectName" xml-path="projects/prj:project/text()">
                    <xml-access-methods get-method="getProject" set-method="setProject" />
                </xml-element>
                <xml-element java-attribute="someString" name="some-string">
                    <xml-access-methods get-method="getSomeString" set-method="setSomeString" />
                    <xml-is-set-null-policy xsi-nil-represents-null="true" null-representation-for-xml="XSI_NIL" is-set-method-name="isSetSomeString">
                        <is-set-parameter value="false" type="java.lang.Boolean" />
                    </xml-is-set-null-policy>
                </xml-element>
                <xml-element java-attribute="aString" name="a-string">
                    <xml-access-methods get-method="getAString" set-method="setAString" />
                    <xml-null-policy null-representation-for-xml="EMPTY_NODE" />
                </xml-element>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

Example: xml-value

The following example will demonstrate how to configure XML direct mappings via XML metadata by using xml-value.

org.example.Price.java

package org.example;
 
public class Price {
    public java.math.BigDecimal price;
    public String currency;
 
    java.math.BigDecimal getPrice() { 
        return price; 
    }
 
    void setPrice(java.math.BigDecimal price) {
        this.price = price; 
    }
}

Deployment XML

<class-mapping-descriptor xsi:type="xml-class-mapping-descriptor">
    <class>org.example.Price</class>
    <alias>Price</alias>
    <attribute-mappings>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>price</attribute-name>
            <read-only>true</read-only>
            <set-method>setPrice</set-method>
            <field name="price-data/text()" xsi:type="node"/>
        </attribute-mapping>
        <attribute-mapping xsi:type="xml-direct-mapping">
            <attribute-name>currency</attribute-name>
            <field name="@currency" xsi:type="node"/>
        </attribute-mapping>
    </attribute-mappings>
    <descriptor-type>aggregate</descriptor-type>
    <default-root-element>price-data</default-root-element>
    <default-root-element-field name="price-data"/>
</class-mapping-descriptor>

XML Instance Document (read)

<?xml version="1.0" encoding="UTF-8"?>
<price-data currency="CAD">123.4560000000000030695446184836328029632568359375</price-data>

XML Instance Document (write)

<?xml version="1.0" encoding="UTF-8"?>
<price-data currency="CAD"/>

org/example/eclipselink-oxm.xml

This XML file demonstrates configuring XML direct mappings on the "org.example.Price" class.

<?xml version="1.0" encoding="US-ASCII"?>
<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm">
    <java-types>
        <java-type name="org.example.Price" xml-accessor-type="FIELD">
            <xml-root-element name="price-data" />
            <java-attributes>
                <xml-value java-attribute="price" read-only="true">
                    <xml-access-methods get-method="getPrice" set-method="setPrice" />
                </xml-value>
                <xml-attribute java-attribute="currency" />
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

Open Issues

This section lists the open issues that are still pending that must be decided prior to fully implementing this project's requirements.

Issue# Owner Description/Notes

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

Future Considerations

During the research for this project the following items were identified as out of scope but are captured here as potential future enhancements. If agreed upon during the review process these should be logged in the bug system.