How to properly delete a complex object using Hibernate?

Question

Here is the problem. When I'm trying to delete a Catalog object from database, Hibernate also removing all Catalog objects with associated Type and Genre Ids. For example, if I’m removing Catalog with Type.id=1 and Genre.id=1 Hibernate delete every Catalogs with such Ids. Any ideas how to fix it? I need to delete only one Catalog object without deleting Type and Genre objects with id=1.

@Entity
@Table(name = "catalog", catalog = "media_store_db")
public class Catalog implements Serializable {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "product_name", length = 100)
    private String productName;

    @ManyToOne(cascade = {CascadeType.ALL})
    @JoinColumn(name = "genre_id", referencedColumnName = "genre_id")
    private Genre genre;

    @ManyToOne(cascade = {CascadeType.ALL})
    @JoinColumn(name = "type_id", referencedColumnName = "type_id")
    private Type type;


@Entity
@Table(name = "genres", catalog = "media_store_db")
public class Genre implements Serializable {

    @Id
    @Column(name = "genre_id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "genre_name")
    private String name;

    @OneToMany(mappedBy = "genre", cascade = CascadeType.ALL)
    Collection<Catalog> catalogs = new ArrayList<Catalog>();

@Entity
@Table(name = "types", catalog = "media_store_db")
public class Type implements Serializable {

    @Id
    @Column(name = "type_id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "type_name")
    private String name;

    @OneToMany(mappedBy = "type", cascade = CascadeType.ALL)
    Collection<Catalog> catalogs = new ArrayList<Catalog>();

My method which delete a Catalog object

public void deleteCatalog(Integer catalogId) {
        Session session = config.getSession();
        Transaction tx = session.beginTransaction();
        session.delete(session.get(Catalog.class, catalogId));
        tx.commit();
        session.close();
}

Jay · Accepted Answer · 2014-03-09 22:24:14Z

1

This is because of Cascade.ALL. If you delete a parent if would also delete all related child if you are using Cascade.ALL.

Instead ALL choose only what you need from the below

CascadeType.PERSIST: cascades the persist (create) operation to associated entities if persist() is called or if the entity is managed

CascadeType.MERGE: cascades the merge operation to associated entities if merge() is called or if the entity is managed

CascadeType.REMOVE: cascades the remove operation to associated entities if delete() is called

CascadeType.REFRESH: cascades the refresh operation to associated entities if refresh() is called

CascadeType.DETACH: cascades the detach operation to associated entities if detach() is called

CascadeType.ALL: all of the above

answered Mar 9, 2014 at 22:24

Jay

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2 Comments

Flavio Over a year ago

If I only need to delete a single Catalog without deleting Type and Genre associated with that Catalog which one of cascade operetion I need to choose? Or maybe I need to change some info in annotation?

Jay Over a year ago

Its a mix and match according to the need. You can add more than one. For example you could start with CascadeType.PERSIST alone. It would Persist all the child objects when you save a parent. And check what happens to delete operation. It would not delete the child. Like that try one by one according to what you need.

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