Question about one-to-many relation

zhlmmc · **Joined:** Wed Jan 24, 2007 10:29 am **Posts:** 5

I have some problem with the one-to-many relation.
I have a Class User and a Class UserLevel. The relation between User and UserLevel is 1-n.
So, I have following configurations:
In User.hbm.xml

Code:

<set name="userLevels" inverse="true">
            <key>
                <column name="user_id" />
            </key>
            <one-to-many class="yuguo.its.data.model.UserLevel" />
        </set>

In User.java

Code:

private Set userLevels = new HashSet(0);

In UserDAO.java

Code:

public User findById( java.lang.Integer id) {
        log.debug("getting User instance with id: " + id);
        try {
            User instance = (User) getSession()
                    .get("yuguo.its.data.model.User", id);
            return instance;
        } catch (RuntimeException re) {
            log.error("get failed", re);
            throw re;
        }
    }

I use User.findById to get an instance of User. Then I use user.getUserLevels() to get the UserLevel set. In the database, I have two UserLevel assigned to the User. But the set returned by user.getUserLevels() is empty.
When I tried UserLevelDAO.getByExample(new UserLevel(User)), the returned list is correct.
My Hibernate version is 3.1.
What's the problem?

Thanks in advance!

Hailong Zhang

dharmendra.pandey · **Posted:** Mon Feb 05, 2007 12:13 am

Hi zhlmmc,

try this.

User instance = (User) getSession()
.get(User.class, id);