Hibernate @OneToMany: PSQLException: ERROR: null value in column

Question

I have two dtos and corresponding dao interfaces which extend JpaRepository

@Entity
@Table(name = "parent")
@NoArgsConstructor
@AllArgsConstructor
@SequenceGenerator(name = "parentSequence", sequenceName = "parent_id_seq",
        allocationSize = 1)
public class ParentDto implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "parentSequence")
    private Long id;
    
    private String name;

    @OneToMany(mappedBy = "parent", targetEntity = Child.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<ChildDto> children;
}


@Entity
@AllArgsConstructor
@SequenceGenerator(name="childSequence", sequenceName = "child_id_seq", allocationSize=1)
@Table(name = "child")
public class ChildDto {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "childSequence")
    private Long id;

    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", nullable = false)
    private ParentDto parent;
}

public interface ParentDao extends JpaRepository<ParentDto, Long> {
}
public interface ChildDao extends JpaRepository<ChildDto, Long> {
}

I have the next request to save mapped to property request (ids should be generated by DB)

{ "parent": { "name": "Bob", "children": [{ "name": "Bob2" }] } }

Executing parentDao.save(request); and getting exception

Caused by: java.sql.BatchUpdateException: Batch entry 0 insert into child (id, name, parent_id) values (1, "Bob2", NULL) was aborted: ERROR: null value in column "parent_id" violates not-null constraint
Detail: Failing row contains (1, "Bob2", NULL). Call getNextException to see other errors in the batch. Caused by: org.postgresql.util.PSQLException: ERROR: null value in column "parent_id" violates not-null constraint Detail: Failing row contains (1, "Bob2", NULL).

Have a look at this, most probably related, question: https://stackoverflow.com/questions/3927091/save-child-objects-automatically-using-jpa-hibernate — Lesrac, Sep 08 '22 at 13:03

score 0 · Answer 1 · answered Sep 08 '22 at 13:04

0

You are cascading persistence from the parent to the child, but the child has no parent. As well as adding a child to the parent make sure you also set the parent on the child. It's important to keep them in sync when declaring bidirectional relationships

child.setParent(parent);

answered Sep 08 '22 at 13:04

johnnyutts

1,349
1
8
11

any other ideas? I have the same problem and my child has a reference to own parent. And it's also doest work – jonua Jan 13 '23 at 08:51

score 0 · Answer 2 · answered May 10 '23 at 13:27

This is an old question, but for new people wondering, the answer by @johnnynutts is actually correct. There are multiple ways to implement a @OneToMany relationship in hibernate. As described in detail by a post from Vlad Mihalcea, these ways are:

Unidirectional @OneToMany
Unidirectional @OneToMany with @JoinColumn
Bidirectional @OneToMany (which is the one used in the question's example)

If you decide to implement the Bidirectional method, then you need keep both connection in sync (update both parent & child) or else you'll get the error on saving.

Hibernate @OneToMany: PSQLException: ERROR: null value in column

2 Answers2