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

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{{EclipseLink_UserGuide
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Please see http://www.eclipse.org/eclipselink/documentation/2.4/moxy/privately_owned_relationships001.htm
|eclipselink=y
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|eclipselinktype=MOXy
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|info=y
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|toc=y
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|api=y
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|apis= * [http://www.eclipse.org/eclipselink/api/latest/javax/xml/bind/annotation/XmlElement.html javax.xml.bind.annotation.XmlElement]
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}}
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=Mapping Privately-Owned One-to-One Relationships=
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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, a '''Customer''' with a one-to-one mapping to a '''PhoneNumber''' would be marshalled as:
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<source lang="xml">
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<customer>
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  <name>Bob Smith</name>
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  <id>1982812</id>
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  <phone-number>
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      <area-code>613</area-code>
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      <number>5550210</number>
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      <extension>20016</extension>
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  </phone-number>
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</customer>
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</source>
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==Mapping to an Element==
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Given the XML schema in this example, the figure below illustrates a one-to-one relationship between two complex types.
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<source lang="xml">
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<?xml version="1.0" encoding="UTF-8"?>
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<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
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  <xsd:element name="customer" type="customer-type"/>
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  <xsd:complexType name="customer-type">
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      <xsd:element name="phone-number" type="phone-type"/>
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  </xsd:complexType>
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  <xsd:complexType name="phone-type">
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      <xsd:element name="area-code" type="xsd:int"/>
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      <xsd:element name="number" type="xsd:int"/>
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      <xsd:element name="extension" type="xsd:int"/>
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  </xsd:complexType>
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</xsd:schema>
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</source>
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[[Image:onetoone.png]]<br><br>
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The following example shows how to annotate your Java class to obtain this mapping with EclipseLink.  By default, any non-simple fields in will be automatically mapped to an element of the same name as the field.  Use the the standard JAXB '''@XmlElement''' annotation.
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<source lang="java">
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@XmlRootElement
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@XmlAccessorType(XmlAccessType.FIELD)
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public class Customer {
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  @XmlElement(name="phone-number")
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  private PhoneNumber phoneNumber;
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  ...
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}
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@XmlAccessorType(XmlAccessType.FIELD)
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public class PhoneNumber {
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  @XmlElement(name="area-code")
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  private Integer areaCode;
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  private Integer number;
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  private Integer extension;
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  ...
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}
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</source>
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The following example shows how to define your mapping information in EclipseLink's OXM metadata format.
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<source lang="xml">
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...
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<java-type name="Customer">
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  <xml-root-element name="customer"/>
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  <java-attributes>
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      <xml-element java-attribute="phoneNumber" name="phone-number" type="PhoneNumber"/>
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  </java-attributes>
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</java-type>
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<java-type name="PhoneNumber">
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  <java-attributes>
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      <xml-value java-attribute="areaCode" name="area-code" type="java.lang.Integer"/>
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      <xml-value java-attribute="number" type="java.lang.Integer"/>
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      <xml-value java-attribute="extension" type="java.lang.Integer"/>
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  </java-attributes>
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</java-type>
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...
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</source>
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=="Self" Mappings==
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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). 
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The following example demonstrates a self mapping declared in annotations.
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<source lang="java">
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@XmlRootElement
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@XmlAccessorType(XmlAccessType.FIELD)
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public class Customer {
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  @XmlPath(".")
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  private PhoneNumber phoneNumber;
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  ...
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}
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public class PhoneNumber {
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  ...
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}
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</source>
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The following below shows a self mapping defined in EclipseLink's OXM metadata format.
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<source lang="xml">
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...
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<java-type name="Customer">
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  <xml-root-element name="customer"/>
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  <java-attributes>
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      <xml-element java-attribute="phoneNumber" type="PhoneNumber" xml-path="."/>
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  </java-attributes>
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</java-type>
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<java-type name="PhoneNumber">
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  ...
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</java-type>
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...
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</source>
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Using a self mapping, EclipseLink produces the following XML:
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<source lang="xml">
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<customer>
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  <area-code>613</area-code>
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  <number>2883000</number>
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  <extension>1547</extension>
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</customer>
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</source>
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{{EclipseLink_MOXy
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|version=2.2.0 DRAFT
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|previous=[[EclipseLink/UserGuide/MOXy/Relationships/Privately Owned|Privately owned]]
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|next=[[EclipseLink/UserGuide/MOXy/Relationships/Privately_Owned/One-to-Many|One-to-many]]
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|up=[[EclipseLink/UserGuide/MOXy/Relationships/Privately Owned|Privately owned]]
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}}
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Latest revision as of 10:21, 8 November 2012

Please see http://www.eclipse.org/eclipselink/documentation/2.4/moxy/privately_owned_relationships001.htm