Problem in Many to Many mapping -

[hildich kilal]

Hello ,
I have two entities User and Role and they have Many to many relationship.
Both are pre - populated with values in database. There is a GUI where we can assign / remove roles to a user.

When i remove roles from an User it works fine and removes the link from join table 'user_role'. But when i add a role to collection in User it also tries to insert it in 'Role' table and throws "org.hibernate.exception.ConstraintViolationException"

Looks like I haven't defined the mapping correctly. ANy pointers will be helpful

Code
User entity mapping to Role

@ManyToMany(cascade = CascadeType.ALL)
  private Set<Role>         roles            = new HashSet<Role>();

Role entity doesn't have any mapping defined to User entity in it.

We have 3 tables User, Role and Use_Role.

To remove add role following is code in DAO.

User existingUserEntity  = (User) persistenceManager.merge(user);
existingUserEntity.getRoles().add(role);

...
...
User existingUserEntity  = (User) persistenceManager.merge(user);					existingUserEntity.getRoles().remove(role);

So remove works fine and clearly deletes entry only from User_Role table.
"Hibernate: delete from user_role where t_user_name=? and roles_name=?"
But adding a role to user throws above mentioned exception and show SQL clearly shows and attempt to add Role entity in Role table.

"Hibernate: insert into role (description, propString, name) values (?, ?, ?)"

Thanks

[Wouter Oet]

How do you get the Role in your example?

[hildich kilal]

Wouter Oet wrote:How do you get the Role in your example?

Role is get as a (collection) of entities and populated in GUI. There it is just a POJO as it is out of PersistenceContext.
After user selects a particular role from select list it is passed as it is a Pojo in DAO. Primary key of Role is 'Name'.

My understanding is that as soon as i add this role in

existingUser.getRoles().add(role);

the the role should also get merged. But that is not happening.
I tried merging the Role explicitely. But then I get NonUniqueObject exception at time of commit.

here is the code from DAO

public final boolean saveUser(final List<User> removeUsers, final List<User> addUsers,
			final Role role) throws SystemException {
		try {
			...

			for (User user : removeUsers) {
				
				User existingUser = (User) persistenceManager.merge(user);
				existingUser.getRoles().remove(role);
				
				log.debug("Removed role from user: " + user.getName());
			}
			for (User user : addUsers) {
				
				User existingUser = (User) persistenceManager.merge(user);
				existingUser.getRoles().add(role);
				log.debug("Added Role to user: " + user.getName());
			}

		}catch(ConstraintViolationException ce){
			log.error("UniqueConstraintException",ce);
			throw new SystemException(ce,"This record has already been modified by another user. "); 
		}
		return true;
	}