Question

Here is my data model (simplified),

public class AddressBook {
    private List<Group> groups = new ArrayList<Group>();
    private List<People> peoples = new ArrayList<People>();

    @OneToMany(mappedBy = "addressbook", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
    public List<Group> getGroups() {
        return groups;
    }

    @OneToMany(mappedBy = "addressbook", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
    public List<People> getPeoples() {
        return peoples;
    }
}


public class Group {
    private AddressBook addressBook;


    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    public void setAddressBook(AddressBook addressBook) {
        this.addressBook = addressBook;
    }
}

public class People {
    private AddressBook addressBook;
    private Group group;

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    public AddressBook getAddressBook() {
        return addressBook;
    }
    public Group getGroup() {
        return group;
    }
}

I want to delete a full group from my addressbook, and all the people belonging to this group. So I do something like:

adressBook.getPeople().removeAll(peopleBelongingToGroupA);
adressBook.getGroups().remove(groupA);

But when my transaction is committed, Hibernate does first:

delete from groups where groupName='groupA';

Instead of deleting the people first. That causes my FOREIGN_KEY constraint between people and group to be violated.

Is there a way to tell hibernate to delete the people first, then the groups? Is there a flaw in my model?

Answer 1

Have you tried putting setting the cascade on each @ManyToOne. You’ve only specified, in many ways, cascade deletion on the AddressBook. This property is for each association I believe.

The EJB3.0 specification is well worth having to hand when writing these beans. See http://jcp.org/en/jsr/detail?id=220

Update:
Reading your datamodel again, there may be a missing annotation on people here that would explain the behaviour. Do you have cascade set on the link with people->group? This would explain why the first statement would first start by trying to delete the group. Presumably you would want an annotation for groups on people that does not cascade?