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EclipseLink 2.2.0, build 'v20110202-r8913' API Reference | ||||||||
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@Target(value={METHOD,FIELD}) @Retention(value=RUNTIME) public @interface OneToOne
Defines a single-valued association to another entity that has
one-to-one multiplicity. It is not normally necessary to specify
the associated target entity explicitly since it can usually be
inferred from the type of the object being referenced. If the relationship is
bidirectional, the non-owning side must use the mappedBy
element of
the OneToOne
annotation to specify the relationship field or
property of the owning side.
The OneToOne
annotation may be used within an
embeddable class to specify a relationship from the embeddable
class to an entity class. If the relationship is bidirectional and
the entity containing the embeddable class is on the owning side of
the relationship, the non-owning side must use the
mappedBy
element of the OneToOne
annotation to specify the relationship field or property of the
embeddable class. The dot (".") notation syntax must be used in the
mappedBy
element to indicate the relationship attribute within the
embedded attribute. The value of each identifier used with the dot
notation is the name of the respective embedded field or property.
Example 1: One-to-one association that maps a foreign key column // On Customer class: @OneToOne(optional=false) @JoinColumn( name="CUSTREC_ID", unique=true, nullable=false, updatable=false) public CustomerRecord getCustomerRecord() { return customerRecord; } // On CustomerRecord class: @OneToOne(optional=false, mappedBy="customerRecord") public Customer getCustomer() { return customer; } Example 2: One-to-one association that assumes both the source and target share the same primary key values. // On Employee class: @Entity public class Employee { @Id Integer id; @OneToOne @MapsId EmployeeInfo info; ... } // On EmployeeInfo class: @Entity public class EmployeeInfo { @Id Integer id; ... } Example 3: One-to-one association from an embeddable class to another entity. @Entity public class Employee { @Id int id; @Embedded LocationDetails location; ... } @Embeddable public class LocationDetails { int officeNumber; @OneToOne ParkingSpot parkingSpot; ... } @Entity public class ParkingSpot { @Id int id; String garage; @OneToOne(mappedBy="location.parkingSpot") Employee assignedTo; ... }
Optional Element Summary | |
---|---|
CascadeType[] |
cascade
(Optional) The operations that must be cascaded to the target of the association. |
FetchType |
fetch
(Optional) Whether the association should be lazily loaded or must be eagerly fetched. |
java.lang.String |
mappedBy
(Optional) The field that owns the relationship. |
boolean |
optional
(Optional) Whether the association is optional. |
boolean |
orphanRemoval
(Optional) Whether to apply the remove operation to entities that have been removed from the relationship and to cascade the remove operation to those entities. |
java.lang.Class |
targetEntity
(Optional) The entity class that is the target of the association. |
public abstract java.lang.Class targetEntity
Defaults to the type of the field or property that stores the association.
public abstract CascadeType[] cascade
By default no operations are cascaded.
public abstract FetchType fetch
public abstract boolean optional
public abstract java.lang.String mappedBy
public abstract boolean orphanRemoval
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EclipseLink 2.2.0, build 'v20110202-r8913' API Reference | ||||||||
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SUMMARY: REQUIRED | OPTIONAL | DETAIL: ELEMENT |