Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
which accompanies this distribution.
The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at
http://www.eclipse.org/org/documents/edl-v10.php.
Contributors:
Linda DeMichiel - Java Persistence 2.1
Linda DeMichiel - Java Persistence 2.0
/*******************************************************************************
* Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Linda DeMichiel - Java Persistence 2.1
* Linda DeMichiel - Java Persistence 2.0
*
******************************************************************************/
package javax.persistence;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import javax.persistence.CascadeType;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.FetchType.EAGER;
Specifies 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;
...
}
Since: Java Persistence 1.0
/**
* Specifies 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 <code>mappedBy</code> element of
* the <code>OneToOne</code> annotation to specify the relationship field or
* property of the owning side.
*
* <p> The <code>OneToOne</code> 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
* <code>mappedBy</code> element of the <code>OneToOne</code>
* annotation to specify the relationship field or property of the
* embeddable class. The dot (".") notation syntax must be used in the
* <code>mappedBy</code> 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.
*
* <pre>
* 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;
* ...
* }
*
* </pre>
*
* @since Java Persistence 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface OneToOne {
(Optional) The entity class that is the target of
the association.
Defaults to the type of the field or property
that stores the association.
/**
* (Optional) The entity class that is the target of
* the association.
*
* <p> Defaults to the type of the field or property
* that stores the association.
*/
Class targetEntity() default void.class;
(Optional) The operations that must be cascaded to
the target of the association.
By default no operations are cascaded.
/**
* (Optional) The operations that must be cascaded to
* the target of the association.
*
* <p> By default no operations are cascaded.
*/
CascadeType[] cascade() default {};
(Optional) Whether the association should be lazily
loaded or must be eagerly fetched. The EAGER
strategy is a requirement on the persistence provider runtime that
the associated entity must be eagerly fetched. The LAZY
strategy is a hint to the persistence provider runtime.
/**
* (Optional) Whether the association should be lazily
* loaded or must be eagerly fetched. The EAGER
* strategy is a requirement on the persistence provider runtime that
* the associated entity must be eagerly fetched. The LAZY
* strategy is a hint to the persistence provider runtime.
*/
FetchType fetch() default EAGER;
(Optional) Whether the association is optional. If set
to false then a non-null relationship must always exist.
/**
* (Optional) Whether the association is optional. If set
* to false then a non-null relationship must always exist.
*/
boolean optional() default true;
(Optional) The field that owns the relationship. This
element is only specified on the inverse (non-owning)
side of the association.
/** (Optional) The field that owns the relationship. This
* element is only specified on the inverse (non-owning)
* side of the association.
*/
String mappedBy() default "";
(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.
Since: Java Persistence 2.0
/**
* (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.
* @since Java Persistence 2.0
*/
boolean orphanRemoval() default false;
}