Hello,

I Have got an issue with bi-directional association and session cache.

Situation is easy for understanding.

There are two entities:


I execute operation which should attach user to some group and then check that user was attached to group (in one transaction):


All this (attaching user to group) is in single transaction.

As far as I understand session cache after saving user contains 2 entities: user with filled group list and group with empty user list. So that's why I have empty user list in group.
How to avoid this situation? Of course I can clear cache before getting group, but is there other solution?

I don't put mapping, because suppose that it's clear enough and it's better to discuss this in more abstract way to determine the best approach to solve this.

Thanks in advance.

This code creates a new group.... so it's not surprising if the group with id=1 is not associated with any user...

And... as you say, it's a bi-directional association, so you'll need to update both ends of the association. Read this chapter in the documentation: http://docs.jboss.org/hibernate/stable/ ... usingbidir

You code should be something like this:



No need to call session.save() since Hibernate will automatically detect changes and save to the database.

Thanks for fast reply!

I did a mistake when wrote

Of course, there should have been

Nevertheless, you understood and gave me advice.

One point that I found while investigating this is that updating both ends of the association is necessary to keep session cache sync. Right?
If I don't update second end of the association and clear session cache then on the next query I get all data linked fine - Hibernate stores and retrieve data correctly.