How do I get Hibernate to delete a many-to-many relation automatically when I have it delete one of the related items?
For example: I have two entities (domain objects), let's say Employee and Project. One or more employees can be involved in one or more projects. The domain objects are mapped to the tables EMPLOYEE and PROJECT respectively. A third table, EMPLOYEE_PROJECT, functions as the coupling between the two, holding only a EMPLOYEE_ID (with a constraint to EMPLOYEE.ID) and a PROJECT_ID (with a constraint to PROJECT.ID).
Imagine I delete a Project using session.delete(myProject). Hibernate complains it can not delete the project, because of the constraint with EMPLOYEE_PROJECT.PROJECT_ID. I want it to delete that coupling as well, without deleting any Employees of course!
Maybe I could move the many-to-many definition to the Project mapping file instead, but then I would have the same problem when deleting an Employee.
Am I overseeing something? Help is much appreciated! Thanks!
[ August 24, 2006: Message edited by: Kjeld Sigtermans ]
Kjeld Sigtermans - SCJP 1.4 - SCWCD 1.4
Joined: Aug 10, 2006
Ok I just solved my own problem yeehaa.. I also created a many-to-many definition in the mapping file for Project, and just like the Employee class has a Set getProjects(), I now added a Set getEmployees() to the Project class. It now works like I'd expect: when deleting a Project, all couplings with Employees are deleted as well, and the Employees in question just remain.
Hi, I tried to explain the solution in my previous message, sorry if I was unclair. Before, I had only defined a many-to-many in Employee. Before posting my message I assumed that is was impossible to also create a many-to-many in Project... but I tried and it worked out perfectly.
I did not implement a cascade attribute in either one. Thanks!