JPA insert objects with null ids

Question

I have the following entities :

@Data
@Entity
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "user")
public class UserEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Integer id;

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "user", cascade = CascadeType.ALL)
    private Collection<AddressEntity> adresses;

    public void addAddresses(Collection<AddressEntity> ad) {
        this.addresses = addresses;
        addresses.forEach(address-> address.setUser(this));
    }

}

@Data
@Entity
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Table(name = "address")
public class AddressEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Integer id;

    @Column(name = "user_id", nullable = false)
    private Integer userId;

    @ManyToOne(optional = false)
    @JoinColumn(name = "user_id", referencedColumnName = "id", nullable = false, insertable = false, updatable = false)
    private UserEntity user;

}

And I save the entities by calling the userRepository :

users.addAdresses(addresses);
userRepository.saveAll(users);

When the user and the addresses don't already exist in the database, I have the following error :

ERROR - ERROR: null value in column "user_id" of relation "address" violates not-null constraint

What do I miss here ?

Answer 1

@Column(name = "user_id", nullable = false)
private Integer userId;

Above code is creating the problem here. You can remove the userId field of AddressEntity as it is not required. JoinColumn annotation added on user field of AddressEntity creates user_id column and saves id of UserEntity.

You can read more about JoinColumn annotation here - https://www.baeldung.com/jpa-join-column.

I executed the following code after removing the userId field from AddressEntity, and I get the below results.

    UserEntity user1 = new UserEntity();
    UserEntity user2 = new UserEntity();
    List<AddressEntity> addresses1 = List.of(new AddressEntity(), new AddressEntity());
    List<AddressEntity> addresses2 = List.of(new AddressEntity(), new AddressEntity());
    user1.addAddresses(addresses1);
    user2.addAddresses(addresses2);
    userRepository.saveAll(List.of(user1, user2));

User Table:

ID
1
2

Address Table:

ID	USER_ID
1	1
2	1
3	2
4	2