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Difference between revisions of "EclipseLink/UserGuide/MOXy/Relationships/Privately Owned/One-to-One"

Line 17: Line 17:
 
   <phone-number>
 
   <phone-number>
 
       <area-code>613</area-code>
 
       <area-code>613</area-code>
       <number>613</number>
+
       <number>5550210</number>
 
       <extension>20016</extension>
 
       <extension>20016</extension>
 
   </phone-number>
 
   </phone-number>

Revision as of 16:55, 19 January 2011

EclipseLink MOXy

Mapping Privately-Owned One-to-One Relationships

This section demonstrates several ways to map a one-to-one relationship between objects. By default, one-to-one relationships are privately-owned in JAXB -- their XML content will appear nested inside the owning element. For example:

<customer>
   <name>Bob Smith</name>
   <id>1982812</id>
   <phone-number>
      <area-code>613</area-code>
      <number>5550210</number>
      <extension>20016</extension>
   </phone-number>
</customer

Mapping to an Element

Given the XML schema in this example, the figure below illustrates a one-to-one relationship between two complex types.

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 
   <xsd:element name="customer" type="customer-type"/>
 
   <xsd:complexType name="customer-type">
      <xsd:element name="phone-number" type="phone-type"/>
   </xsd:complexType>
 
   <xsd:complexType name="phone-type">
      <xsd:element name="area-code" type="xsd:int"/>
      <xsd:element name="number" type="xsd:int"/>
      <xsd:element name="extension" type="xsd:int"/>
   </xsd:complexType>
 
</xsd:schema>

Onetoone.png

The following example shows how to annotate your Java class to obtain this mapping with EclipseLink. Use the the standard JAXB @XmlElement annotation.

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Customer {
   @XmlElement(name="phone-number")
   private PhoneNumber phoneNumber;
 
   ...
}
 
@XmlAccessorType(XmlAccessType.FIELD)
public class PhoneNumber {
   @XmlElement(name="area-code")
   private Integer areaCode;
 
   private Integer number;
 
   private Integer extension;
 
   ...
}

The following example shows how to define your mapping information in EclipseLink's OXM metadata format.

...
<java-type name="Customer">
   <xml-root-element name="customer"/>
   <java-attributes>
      <xml-element java-attribute="phoneNumber" name="phone-number" type="PhoneNumber"/>
   </java-attributes>
</java-type>
 
<java-type name="PhoneNumber">
   <java-attributes>
      <xml-value java-attribute="areaCode" name="area-code" type="java.lang.Integer"/>
      <xml-value java-attribute="number" type="java.lang.Integer"/>
      <xml-value java-attribute="extension" type="java.lang.Integer"/>
   </java-attributes>
</java-type>
...


"Self" Mappings

EclipseLink allows you to configure your one-to-one mapping so the data from the target object will appear inside the source object's XML element. Using the previous example, the PhoneNumber information would appear directly under the customer element, and not wrapped in a phone-number element. This is referred to as a "self" mapping, and is achieved by setting the target object's XPath to . (dot).

The following example demonstrates a self mapping declared in annotations.

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Customer {
   @XmlPath(".")
   private PhoneNumber phoneNumber;
 
   ...
}
 
public class PhoneNumber {
   ...
}

The following below shows a self mapping defined in EclipseLink's OXM metadata format.

...
<java-type name="Customer">
   <xml-root-element name="customer"/>
   <java-attributes>
      <xml-element java-attribute="phoneNumber" type="PhoneNumber" xml-path="."/>
   </java-attributes>
</java-type>
 
<java-type name="PhoneNumber">
   ...
</java-type>
...

Using a self mapping, EclipseLink produces the following XML:

<customer>
   <area-code>613</area-code>
   <number>2883000</number>
   <extension>1547</extension>
</customer>


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Version: 2.2.0 DRAFT
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