CODEWITHSUNDEEP
javaspringspring-data-jpaspring-datahibernate-mapping
Demon4i
Demon4i

Reputation: 27

Hibernate OnetoMany and ManyToOne throw exception

I'm trying to make simple one to many relationship but hibernate is throwing error, no idea what to do.

Class Product:

public class Products {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @ManyToOne()
    @JoinColumn(name = "user_id", foreignKey = @ForeignKey(name = "fk_user"))
    private Users users;

}

and Class Users:

public class Users {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long Id;


    @OneToMany()
    @JoinColumn(name = "product_id", foreignKey = @ForeignKey(name = "fk_product_id"))
    private List<Products> productsList = new ArrayList<>();

}

I got error: Error executing DDL "alter table products drop constraint fk_user" via JDBC Statement

Upvotes: 0

Views: 695

Answers (2)

Andronicus
Andronicus

Reputation: 26076

Since the foreign key is on the child side (Products class), you can drop it on the parent side and reference to child as being the owning side:

public class Users {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long Id;


    @OneToMany(mappedBy="users")
    private List<Products> productsList = new ArrayList<>();

}

Upvotes: 1

Martin
Martin

Reputation: 2255

Here is a working example of such relationship :

Drawer class :

@OneToMany (mappedBy="drawer", fetch = FetchType.LAZY, cascade = CascadeType.REMOVE, orphanRemoval = true)
private Set<Pocket> pockets;

Pocket class :

@ManyToOne (fetch=FetchType.EAGER)
@JoinColumn(name = "id_drawer", nullable = false)
private Drawer drawer;

Upvotes: 2

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