NULL value somehow being assigned to ID field in H2 database SQL statement

Question

I'm working on an H2 database, trying to get it to accept input from a webpage, and it keeps giving me the following error:

Caused by[m: org.h2.jdbc.JdbcSQLIntegrityConstraintViolationException: NULL not allowed for column "ID"; SQL statement:
insert into BOOK (ID, AUTHOR, GENRE, ILLUSTRATOR, SERIES, TITLE) values (default, ?, ?, ?, ?, ?) [23502-214]

and I have no idea where it's getting this NULL value from. I've got the model kitted out

@Entity
@Table(name = "BOOK")
public class Book {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "ID")
    private Long id;

and the DAO is set up to give me a non-null value

@Repository
public class DAOImpl implements DAO {

    @Autowired
    private SessionFactory sessionFactory;

    public void saveBook(Book book) {
        book.setId(0L);
        
        Session s = sessionFactory.getCurrentSession();
        s.save(book);
    }

It just seems like the NULL is coming out of nowhere. What am I missing?

Answer 1

You need to check definition of your table. Because you use GenerationType.IDENTITY , the ID column must be defined as an identity column :

CREATE TABLE BOOK (
    ID BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    .....
);

If you want to prevent attempts to insert custom values instead of generated ones, you can use GENERATED ALWAYS AS IDENTITY instead.