EclipseLink/UserGuide/MOXy/Relationships/Privately Owned/One-to-One

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Mapping One-to-One Relationships

This section demonstrates several ways to map a one-to-one relationship between objects.

Mapping to a Complex Type

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="address" type="address-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>

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

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

The example below shows how to 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 such that the data from the target object will appear inside the source object's XML element. This is referred to as a "self" mapping, and is achieved by setting the target object's XPath to ".". The following example demonstrates a self mapping declared in annotations.

@XmlRootElement
public class Customer {
   @XmlElement(name="phone-number")
   @XmlPath(".")
   public PhoneNumber phoneNumber;
}
 
public class PhoneNumber {
   ...
}

The example below shows a self mapping defined on EclipseLink 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-type>
...

Using a self mapping, the following XML will be produced:

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

Working with Null Values

Version: 2.2.0 DRAFT
Other versions...

Privately owned	Privately owned	One-to-many
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