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How to use manytoone jpa and hibernate association?


Asked by Melissa Coffey on Dec 05, 2021 Hibernate



When using JPA and Hibernate, it’s very important to know how to map and use the ManyToOne association since it’s the most comment relationship. Using FetchType.LAZY, by default, is a very useful practice, as the fetching strategy should be set on a per-use case basis, not globally.
Just so,
To establish this relationship, @ManyToOne annotation is used in the source entity class. It is placed on the filed/property of the target entity. On the target side, we don't need to use any relational annotation unless it's a bidirectional association.
Accordingly, When using JPA and Hibernate, the @ManyToOne annotation allows you to map a Foreign Key column: The @JoinColumn annotation allows you to specify the Foreign Key column name.
Moreover,
@Entity annotation is required to specify a JPA and Hibernate entity @Id annotation is required to specify the identifier property of the entity @OneToMany and @ManyToOne defines a one-to-many and many-to-one relationship between 2 entities.
Consequently,
JPA - ManyToOne relationship. Similar to one-to-one association, many-to-one association supports a source entity having a reference of another entity (the target entity), but unlike one-to-one association, many-to-one association also supports multiple instances of the source entity sharing a single target entity instance.