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@Target({METHOD,FIELD}) @Retention(RUNTIME) public @interface ManyToOne
Specifies a single-valued association to another entity class that has many-to-one multiplicity. It is not usually necessary to specify the 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
OneToMany
entity side must use themappedBy
element to specify the relationship field or property of the entity that is the owner of the relationship.A
ManyToOne
association usually maps a foreign key column or columns. This mapping may be specified using theJoinColumn
annotation. Alternatively, an optionalOneToOne
association is sometimes mapped to a join table using theJoinTable
annotation.The
ManyToOne
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, the non-owningOneToMany
entity side must use themappedBy
element of theOneToMany
annotation to specify the relationship field or property of the embeddable field or property on the owning side of the relationship. 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: {@snippet :
- 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.boolean
optional
(Optional) Whether the association is optional.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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optional
boolean optional
(Optional) Whether the association is optional. If set to false then a non-null relationship must always exist.May be used in schema generation to infer that the mapped foreign key column is
not null
.- Default:
- true
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