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Difference between revisions of "EclipseLink/UserGuide/MOXy/Relationships/Bidirectional Relationships"
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'''@XmlInverseReferences''' must specify the '''mappedBy''' attribute, which indicates the property on the opposite side of the relationship. | '''@XmlInverseReferences''' must specify the '''mappedBy''' attribute, which indicates the property on the opposite side of the relationship. | ||
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In this example, an '''Employee''' has a collection of '''PhoneNumbers''', and each '''PhoneNumber''' has a back-pointer back to its '''Employee''': | In this example, an '''Employee''' has a collection of '''PhoneNumbers''', and each '''PhoneNumber''' has a back-pointer back to its '''Employee''': | ||
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// p.setEmployee(emp); | // p.setEmployee(emp); | ||
</source> | </source> | ||
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'''@XmlInverseReference''' back-pointers can be used with the following types of mappings: | '''@XmlInverseReference''' back-pointers can be used with the following types of mappings: | ||
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* [[EclipseLink/UserGuide/MOXy/Relationships/Shared_Reference/Keys_and_Foreign_Keys/Single_Key|Single Key Relationships]] | * [[EclipseLink/UserGuide/MOXy/Relationships/Shared_Reference/Keys_and_Foreign_Keys/Single_Key|Single Key Relationships]] | ||
* [[EclipseLink/UserGuide/MOXy/Relationships/Shared_Reference/Keys_and_Foreign_Keys/Composite_Key|Composite Key Relationships]] | * [[EclipseLink/UserGuide/MOXy/Relationships/Shared_Reference/Keys_and_Foreign_Keys/Composite_Key|Composite Key Relationships]] | ||
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'''@XmlInverseReference''' can be particularly useful when mapping JPA entities to XML. For an example, please see [[EclipseLink/Examples/MOXy/JPA/Relationships|Binding JPA Relationships to XML]]. | '''@XmlInverseReference''' can be particularly useful when mapping JPA entities to XML. For an example, please see [[EclipseLink/Examples/MOXy/JPA/Relationships|Binding JPA Relationships to XML]]. |
Revision as of 14:53, 19 April 2011
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Key API
Bidirectional Relationships
In order to map bidirectional relationships in EclipseLink MOXy, the back-pointer must be annotated as an @XmlInverseReference. Without this annotation, the cyclic relationship will result in an infinite loop during marshalling.
@XmlInverseReferences must specify the mappedBy attribute, which indicates the property on the opposite side of the relationship.
In this example, an Employee has a collection of PhoneNumbers, and each PhoneNumber has a back-pointer back to its Employee:
@XmlAccessorType(XmlAccessType.FIELD) public class Employee { private String name; private List<PhoneNumber> phones = new ArrayList<PhoneNumber>(); ... } @XmlAccessorType(XmlAccessType.FIELD) public class PhoneNumber { private String number; @XmlInverseReference(mappedBy="phones") private Employee employee; ... }
In addition, when using @XmlInverseReference, it is not necessary to explicitly set the back-pointer in your Java code; EclipseLink will do this for you automatically:
Employee emp = new Employee(); emp.setName("Bob Smith"); PhoneNumber p = new PhoneNumber(); p.setNumber("555-1212"); emp.getPhones().add(p); // Not Necessary // p.setEmployee(emp);
@XmlInverseReference back-pointers can be used with the following types of mappings:
- One-To-One Relationships
- One-To-Many Relationships
- Single Key Relationships
- Composite Key Relationships
@XmlInverseReference can be particularly useful when mapping JPA entities to XML. For an example, please see Binding JPA Relationships to XML.