Hibernate - delete linked entity

Question

I have 2 entites:

@Entity
@Table(name="product")
public class Product {
    private Long id;
    private Set<Upgrade> upgrade;

    @Id
    @Column(name="id")
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    @ManyToMany(mappedBy = "products",
                targetEntity = Upgrade.class,
                cascade = CascadeType.REFRESH,
                fetch = FetchType.EAGER)
    public Set<Upgrade> getUpgrade() {
        return upgrade;
    }

    public void setUpgrade(Set<Upgrade> upgrade) {
        this.upgrade = upgrade;
    }
}

and

@Entity
@Table(name="upgrade")
public class Upgrade {
    private Long id;
    private Set<Product> products;

    @Id
    @Column(name="id")
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    @ManyToMany(targetEntity = Product.class, cascade = CascadeType.REFRESH, fetch = FetchType.EAGER)
    @JoinTable(name = "upgrade_product",
               joinColumns = @JoinColumn(name = "upgrade_id"),
               inverseJoinColumns = @JoinColumn(name="product_id"))
    public Set<Product> getProducts() {
        return products;
    }

    public void setProducts(Set<Product> products) {
        this.products = products;
    }
}

My data creates these so that a product contains a set of multiple upgrades.

i.e. P1 {U1, U2, U3, U4} P2 {U1, U3, U5, U7}

If I delete an upgrade, then everything is fine. It is just removed from the product. However, if I delete a product then it attempts to delete all of the linked upgrades.

How do I get this to be able to delete the product and leave the upgrades in place.

Matt Ball · Accepted Answer · 2011-08-12 13:04:41Z

3

Before you delete the Product, clear its Set<Upgrade> and save the Product. Something like:

public void delete(Product p)
{
    p.setUpgrade(Collections.emptySet());
    entityManager.remove(entityManager.merge(p));
}

answered Aug 12, 2011 at 13:04

Matt Ball

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5 Comments

rit Over a year ago

merge is only necessary if the product is not already in the persistence context.

JB Nizet Over a year ago

That doesn't explain why it's needed and why it isn't when deleting an upgrade.

Matt Ball Over a year ago

@JB because the Product is the parent side of the relationship, so Hibernate sees products as owning updates.

JB Nizet Over a year ago

@Matt: There is no cascade delete on the association, so Hibernate shouldn't delete the upgrades, unless I miss something.

Matt Ball Over a year ago

@JB oh, I completely missed that the OP had actually specified CascadeType.REFRESH. Hmm...

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