Many-to-Many junction table not being updated

alistair · **Posted:** Tue Mar 09, 2004 5:43 am

Using: Hibernate 2.1.2, MySQL 4

Code:

[net.sf.hibernate.engine.Cascades] processing cascades for: X.model.User
[net.sf.hibernate.engine.Cascades] cascading to collection: X.model.User.roles
[net.sf.hibernate.engine.Cascades] cascading to saveOrUpdate()
[net.sf.hibernate.engine.Cascades] version unsaved-value strategy UNDEFINED
[net.sf.hibernate.engine.Cascades] id unsaved-value strategy NULL

I have a many-to-many relationship between User and Role.
I'm trying to remove a Role from a User but it's not doing anything to the junction table.
Does the error messages above hold any significance with regards to my problem ?

My mapping document:

Code:

    <class
        name="X.model.User" table="user" ...>
       <set
            name="roles"
            table="user_role"
            lazy="false"
            inverse="true"
            cascade="all"
            sort="unsorted"
        >
              <key column="user_id"/>
              <many-to-many
                  class="X.model.Role"
                  column="role_id"
                  outer-join="auto"
              />
        </set>    
        ---o<--- snipped for brevity -----
    </class>

    <class
        name="X.model.Role" table="role" ...>
        <set
            name="users"
            table="user_role"
            lazy="false"
            inverse="false"
            cascade="all"
            sort="unsorted"
        >
              <key
                  column="role_id"   />

              <many-to-many
                  class="X.model.User"
                  column="user_id"
                  outer-join="auto"
              />
        </set>
        ---o<--- snipped for brevity -----
    </class>

michael · **Posted:** Tue Mar 09, 2004 6:07 am

Are you removing the associations from both collections?

alistair · **Posted:** Tue Mar 09, 2004 11:11 pm

OK. I am removing the association from both side.

i.e. User.removeARole(Role r) does two things:

a) Role.removeAUser(this)
b) users.remove( r )

I found out that line (a) fails.

More questions:
- Does the order matter (a before b, b before a) ?
- I can't fathom why line (a) fails because the hashCode() of the User instance matches the one in member Role.users ? Does CGLIB do anything strange to the equals method ? Note that outside of Hibernate, I can safely add a User into a HashSet and remove it.

Regards,

Alistair

alistair · **Posted:** Wed Mar 10, 2004 5:04 am

OK. I'm able to remove from both collections now BUT to make this work; I had to *NOT* override equals/hashCode and use the default reference equality.

However, in my session bean method, it does not update the Database in any way.

Code:

session.saveOrUpdate( theUser );

Some extracts of the log:

Code:

Processing unreferenced collections
Scheduling collection removes/(re)creates/updates
Flushed: 0 insertions, 2 updates, 0 deletions to 2 objects
Flushed: 0 (re)creations, 1 updates, 0 removals to 2 collections

alistair · **Posted:** Wed Mar 10, 2004 10:27 am

OK. The only time I could get rows deleted from the junction table, user_role is by setting the cascade option for class User to "all-delete-orphan". Unfortunately it also deleted the record in Role's table. But I want Role's lifecycle to be independent of Users. Also can anyone offer advice on why I cannot override the hash/equals of my class & especially why relying on the default reference equality in Object is working for me in this case ?

Regards,

Alistair

emmanuel · **Posted:** Wed Mar 10, 2004 5:14 pm

Try to double check your equals/hashCode implementation, there should be something wrong

alistair · **Posted:** Wed Mar 10, 2004 10:54 pm

Merci mille fois Emmanuel!

Voila mes hashCode() and equals():-

Code:

public boolean equals(Object obj) {

  if (this == obj)
    return true;

  if((obj == null) || (obj.getClass() != this.getClass()))
    return false;

  User other = (User) obj;
    return new EqualsBuilder()
     .append(getUserName(), other.getUserName())
     .isEquals();
}

public int hashCode() {
    return new HashCodeBuilder(17, 37)
    .append(getUserName())
    .toHashCode();
}

Mes meilleures amiti

emmanuel · **Posted:** Fri Mar 12, 2004 2:00 pm

usually instanceof is used.
Does this help http://www.hibernate.org/109.html