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EclipseLink/UserGuide/MOXy/Relationships/Privately Owned/One-to-One
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Contents
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 public PhoneNumber phoneNumber; } @XmlRootElement(name="phone-number") 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"> <xml-root-element name="phone-number"/> <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> ...
One-to-One Composite Collection Mapping
With EclipseLink Annotations
Use the @OneToOne annotation:
@Entity public class Employee { @OneToOne(mappedBy="resident") private Address residence; }
Use the EclipseLink extension @XmlInverseReference to map the back-pointer:
@Entity public class Address { @OneToOne @JoinColumn(name="E_ID") @XmlInverseReference(mappedBy="residence") private Employee resident; }