inverse=true in JPA annotations

Question

In my application I use JPA 2.0 with Hibernate as the persistence provider. I have a one-to-many relationship between two entities (using a @JoinColumn and not @JoinTable). I wanted to know how could I specify inverse=true (as specified in hbm.xml) in JPA annotations to reverse the relationship owner.

Thank you.

Answer 1

I found an answer to this. The mappedBy attribute of @OneToMany annotation behaves the same as inverse = true in the xml file.

Answer 2

The attribute mappedBy indicates that the entity in this side is the inverse of the relationship, and the owner resides in the other entity. Other entity will be having @JoinColumn annotaion and @ManyToOne relationship. Hence I think inverse = true is same as @ManyToOne annotation.

Also inverse=”true” mean this is the relationship owner to handle the relationship.

Answer 3

by using mappedBy attribute of @OneToMany or @ManyToMany we can enable inverse="true" in terms of annotation. For example Branch and Staff having one-to-many relationship

@Entity
@Table(name = "branch")
public class Branch implements Serializable {
    @Id
    @Column(name = "branch_no")
    @GeneratedValue(strategy = GenerationType.AUTO)
    protected int branchNo;
    @Column(name = "branch_name")
    protected String branchName;
    @OneToMany(mappedBy = "branch") // this association is mapped by branch attribute of Staff, so ignore this association
    protected Set<Staff> staffSet;
    
    // setters and getters
}
@Entity
@Table(name = "staff")
public class Staff implements Serializable {
    @Id
    @Column(name = "staff_no")
    @GeneratedValue(strategy = GenerationType.AUTO)
    protected int staffNo;
    @Column(name = "full_name")
    protected String fullName;
    @ManyToOne
    @JoinColumn(name = "branch_no", nullable = true)
    protected Branch branch;

    // setters and getters
}