Spring data with hibernate: multiple row insert in one-to-many entity without cascade

Question

I’m using spring data and hibernate as JPA implementation with spring boot. I’m new to this. I have an entity where I’m maintaining the mapping between two entities which already exist and entries into this mapping only come in at the time of a specific update.

@Entity
@Table(name = "song_genres")
public class SongGenres {

    public SongGenres(Song song, List<Genre> genres) {
        this.genres = genres;
        this.song = song;
    }

    public SongGenres() {
//        Empty constructor as required by hibernate
    }

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

    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "song_id")
    private Song song;

    @OneToMany(fetch = FetchType.LAZY)
    @JoinColumn(name = "genre_id")
    private List<Genre> genres;

    public List<Genre> getGenres() {
        return genres;
    }
}

I’m trying to insert all the genre values associated with a song at once, using

SongGenres songGenres = new SongGenres(song, genres);
songGenresRepository.save(songGenres);

but this is giving an error that

java.sql.SQLException: Field 'genre_id' doesn't have a default value

and the sql logs show a single row insert

Hibernate: insert into song_genres (song_id) values (?)

How is multiple row insert in one-to-many achieved without cascade?

score 0 · Answer 1 · edited May 23 '17 at 10:30

For now, I changed the entity definition since there isn't much difference between the two

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

@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "chapter_id")
private Chapter chapter;

@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "genre_id", nullable = false)
private Genre genre;

and the save operation becomes

    List<ChapterGenre> chapterGenres = new ArrayList<>();
    for (Genre genre : genres) {
        chapterGenres.add(new ChapterGenre(chapter, genre));
    }
    chapterGenreRepository.save(chapterGenres);

From this one, concluded there isn't much of a difference from spring's implementation point of view.

Although this ain't best performance mysql-wise. Would be interesting if spring data comes up with a simple single insert API.

Chapter - Song... whichever is easier to understand but interchangeable between this answer and the question — AA_PV, Dec 02 '16 at 08:33

score 0 · Answer 2 · answered Dec 01 '16 at 09:05

0

Just define CASCADE type for your List here "List genres" Add No of Items in list and persist main entity. You can read more about it here

Eg:

@OneToMany(cascade = CascadeType.ALL, mappedBy = "visitId")
private Collection<SampleData> lstSampleData;

answered Dec 01 '16 at 09:05

MyTwoCents

7,284
3
24
52

Hey thanks for answering, like I've mentioned in the question, both entities already exist and it is a specific update which creates the mapping between the two. Else I would've maintained the relation in one and cascaded like you suggest. – AA_PV Dec 02 '16 at 08:35

Spring data with hibernate: multiple row insert in one-to-many entity without cascade

2 Answers2