Hello,

I am using hibernate 3.0. I have mapped a bidirectional many to many association beetwen two tables using an association table. My query are working fine, so my mapping seems ok. However, I just don´t know how to create an association by code.
I have classes A and B. A has a property called bSet and b has a property called aSet. If I just use:
A a = session.load(...);
B b = session.load(...);
a.getBSet().add(b); // and/or b.getASet().add(a);
session.save(a);


I get an error saying that there is alredy an object with the same ID. However, I have NO ROWS in my relation table in database.
What am I doing wrong?

You should use save() only for new objects. Since your objects came from persistence (session.load()), you should use session.update(a) instead. Hibernate will insert/delete rows from the link table for you.

As hlfsousa said, you should understand that the session is a cache for proxified objects.

So, you could do


Instead of trying to save your object, there's no need to (re)do it.

But, there's no reason why the save raises an exception in your code. When you ask for the save of an object that's already a reference present in the cache, nothing is just done...

So could you be a bit more precise about what you do, your mappings, etc...