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@Target({METHOD,FIELD}) @Retention(RUNTIME) public @interface OneToOne
Specifies a single-valued association to another entity class that has one-to-one multiplicity. It is not usually 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 theOneToOne
annotation to specify the relationship field or property of the owning side.A
OneToOne
association usually maps a unique foreign key relationship, either a foreign key column or columns with a unique constraint, or a relationship via a shared primary key. TheJoinColumn
annotation may be used to map the foreign key column or columns. Alternatively, an optionalOneToOne
association is sometimes mapped to a join table using theJoinTable
annotation.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 themappedBy()
element of theOneToOne
annotation to specify the relationship field or property of the embeddable class. The dot (.
) notation syntax must be used in themappedBy()
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 {@snippet : // On Customer class:
- Since:
- 1.0
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Optional Element Summary
Optional Elements Modifier and Type Optional Element Description 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.
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cascade
CascadeType[] cascade
(Optional) The operations that must be cascaded to the target of the association.By default no operations are cascaded.
- Default:
- {}
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fetch
FetchType fetch
(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.
If not specified, defaults to
EAGER
.- Default:
- jakarta.persistence.FetchType.EAGER
- The
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