Hibernate does not delete a DB record when an entity is removed from a collection

Question

Simply removing an entity from a collection of related entities, will not delete the database record, right?

for example:

currentUser.getBooks().remove(thisBook);
userDAO.update(currentUser);

won't delete the record from the DB

Do I have to always explicitly go to the bookDAO and say session.delete(thisBook) every time? I though that Hibernate is much smarter than that and does cascading checks when a parent entity is saved or updated.

How do I resolve this?

You need to set orphanRemoval tto true. Then removing element from collection will remove it from db — Volodymyr Levytskyi, Jul 11 '13 at 07:49

score 5 · Accepted Answer · answered Feb 06 '12 at 10:34

Removing entity Book from the books collection in entity User just removes the relationship between the two entities (Book and User), not the Book entity instance.

The CASCADE clause is also not what you are looking for. Cascading means that if User has books, that is a collection of Book instances, when you remove a User instance, then the book instances are removed as well.

So, read getBooks().remove(thisBook) as remove this book from this collection and not from the database.

And yes, if you want to remove the book you have to use session.remove(book) (or the facility in you DAO).

score 2 · Answer 2 · answered Feb 06 '12 at 10:12

2

You need to specify the cascade type on your relationship.

examples here: http://www.mkyong.com/hibernate/hibernate-cascade-example-save-update-delete-and-delete-orphan/

answered Feb 06 '12 at 10:12

unludo

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I did. I tried anything. CASCADE works only on parent deletion. – Preslav Rachev Feb 06 '12 at 10:14
Did you try this: http://stackoverflow.com/questions/199428/hibernate-delete-cascade – unludo Feb 06 '12 at 10:19

score 0 · Answer 3 · answered Feb 06 '12 at 10:08

0

It all depends on the cascade attribute that you've defined on your books collection.

answered Feb 06 '12 at 10:08

Kurt Du Bois

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Hibernate does not delete a DB record when an entity is removed from a collection

3 Answers3