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− | When binding JPA entities to XML, there are MOXy extensions will help you map a bidirectional relationship | + | When binding JPA entities to XML, there are MOXy extensions will help you map a bidirectional relationship. |
In this sample model, notice that '''Customer''' has a relationship to '''Address''', and '''Address''' has a relationship ''back'' to '''Customer'''. In JPA, one direction of the relationship is mapped (the '''customer''' property on '''Address''); the other direction specifies a mapping to leverage. | In this sample model, notice that '''Customer''' has a relationship to '''Address''', and '''Address''' has a relationship ''back'' to '''Customer'''. In JPA, one direction of the relationship is mapped (the '''customer''' property on '''Address''); the other direction specifies a mapping to leverage. |
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Bidirectional Relationships
When binding JPA entities to XML, there are MOXy extensions will help you map a bidirectional relationship.
In this sample model, notice that Customer' has a relationship to Address, and Address has a relationship back to Customer. In JPA, one direction of the relationship is mapped (the customer property on Address); the other direction specifies a mapping to leverage.
Sample Model
import javax.persistence.*; @Entity public class Customer { @Id private long id; @OneToOne(mappedBy="customer", cascade={CascadeType.ALL}) private Address address; } import javax.persistence.*; @Entity public class Address implements Serializable { @Id private long id; @MapsId @OneToOne @JoinColumn(name="ID") private Customer customer; }
To marshal these objects to XML, mark one direction @XmlTransient' to prevent a JAXB infinite loop during marshalling. Normally, during unmarshalling (from XML-to-object), you are responsible for populating the back pointer
import javax.persistence.*; import javax.xml.bind.annotation.*; @Entity public class Address implements Serializable { @Id private long id; @OneToOne @JoinColumn(name="ID") @MapsId @XmlTransient private Customer customer; }
@XMLInverseReference
With the @XmlInverseReference annotation, MOXy will populate the back pointer automatically. In this sample, notice that the @XmlInverseReference annotation leverages the same "mappedBy" concept.
import javax.persistence.*; import org.eclipse.persistence.oxm.annotations.*; @Entity public class Address implements Serializable { @Id private long id; @OneToOne @JoinColumn(name="ID") @MapsId @XmlInverseReference(mappedBy="address") private Customer customer; }