Problem with CascadeTypes

ger_eire · **Joined:** Sat Mar 14, 2009 10:48 am **Posts:** 7

Hi,

I'm still getting used to Hibernate but am currently having a little bother with deleting an object in a many-to-many relationship.

The functionality I have between the two models is pretty basic. Lets just say the two models are Product and Category, so many products can have many categories and vice versa.

If I delete one product, I do not wish to delete the categories it references and vice versa. The two tables use an association table since its a many-to-many relationship.

I've tried several different CascadeTypes and none seem to work correctly.

Using cascadeType.MERGE produces the following error:

Cannot delete or update a parent row: a foreign key constraint fails

CascadeType.ALL deletes more than 1 row incorrectly (ie. a record in the same table if they share a common attribute)

Using NO cascadeType returns the following error:

org.hibernate.ObjectDeletedException: deleted entity passed to persist manyToMany

and CascadeType.PERSIST throws an exception also:

org.hibernate.TransientObjectException: object references an unsaved transient instance

Sorry for the long-winded explanation but if anyone could help with this, I'd more than appreciate it!

Thanks.

ger_eire · **Joined:** Sat Mar 14, 2009 10:48 am **Posts:** 7

I should also mention that if I specify the following on BOTH models:

@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, mappedBy = "products")

I get an error also:

java.sql.BatchUpdateException: Cannot delete or update a parent row: a foreign key constraint fails (`lportal/ten_category_product`, CONSTRAINT `FKEF22751352CAE5BF` FOREIGN KEY (`product_fk`) REFERENCES `ten_product` (`id`))

ger_eire · **Joined:** Sat Mar 14, 2009 10:48 am **Posts:** 7

Dont wanna sound impatient guys, but I seriously need help with this asap :)

Thanks again.

littypreethkr · **Posted:** Mon Mar 23, 2009 9:05 am

The best thing to do is put a CascadeType Persist, merge and save-update on the primary end of relation (the one with no mappedBy)

Specify mappedBy only on one side.

Quote:

Using cascadeType.MERGE produces the following error:

Cannot delete or update a parent row: a foreign key constraint fails

Please note that before deleting the object you will have to unlink all the many-to-many associations.

Something like:

Code:

item.removeFromAllCategories();
session.delete(item);