I've been troubleshooting a problem with hibernate for the last few days.

I have a parent object that has a composite key. This object has a collection (bag) of children, all of which also have a composite key.

All objects seem to get loaded, but when i call parent.getChildren, it's size is 0, even though i can see the children objects getting loaded.

After trying mapping many diff ways, i changed out my jars to 2.03. Works fine. I suspect some cglib issues, but i don't know enough about the hibernate source yet.

Model:

Visit has 1-m relation to visit-role

xml for visit (excerpt)


Thanks!
James

Be sure to remove *every* old libs from hibernate 2.0 and replace them by Hibernate 2.1 ones (including cglib).
If the children are actually loaded, check your visitRoles getter and setter, it might be somehow broken (usual symptoms).

Thanks for the tips. I rechecked my classpath, and I am certain i'm not using a mix of jars. The setter/getter pair for the collection is fine.

Still having the same issue. There is no problem when using 2.03, but there is with 2.11. Any other suggestions out there?

---James

some extra info, as i spent some time tracing the source code... lots to learn! At the end of this method, the List does have my expected results in it. It just never gets assigned to the field in my object with the collection on it.

Thanks

Sounds like there might be a problem with your equals() / hashCode() implementation. (Remember that the composite-id is also the key of the collection.)

Try

(1) checking your equals()/hashCode()
(2) changing to a non-composite-id

If neither of these fixes works (ie. if the problem still occurs without a composite-id), submit a very simple test main() method to JIRA, so that someone can take a look.

(If it works for a non-composite-id, the problem is certainly with your equals/hashCode)

Thanks Gavin, but we unfortuneately can't change the key. Can i still submit to JIRA? I've worked with Hibernate on about 4 projects now, and unfortuneately, this is one project where i can't make the datamodel more hibernate friendly, by losing the composite keys...

The code DOES seem to work in 2.03. I can get around the problem by manually loading this one dependent collection using session.find, but of course i'd rather have the mapping take care of it for me, as it makes the code so much simpler to read. We have checked/re-checked our equals/hashcode methods, and they are Josh Block friendly.

Thanks for HIbernate! It has made it possible to be object oriented in my domain model!

James

Just FYI, a fellow programmer here is having a similar problem, yet I'm not. (collection not loading.) We've recently upgraded to 2.1.1. (not sure what version she was on before)

???!

Not even for a test???



No, not until you have followed my instructions.



It is not at all impossible that a broken hashCode() problem might not have manifested itself previously.

Please do as I told you: try the same code out with a noncomposite-id, and, if it still doesn't work, then submit to JIRA. Otherwise, if it works, the bug is in your code.

I have the same problem while loading collections of an object with a composite id. I'm using hashcode - equals utils from apache commons, so i guess there shouldn't be trouble with that:

/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object o) {
if ( !(o instanceof PathId) ) {
return false;
}
PathId rhs = (PathId) o;
return new EqualsBuilder()
.appendSuper(super.equals(o))
.append(context, rhs.context)
.append(token, rhs.token)
.isEquals();
}

/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
return new HashCodeBuilder(43, 5).
append(context).
append(token).
toHashCode();
}

furthermore, I performed a test with changing the composite-id to a regular one and the collection was correctly loaded? I wonder what happened with this thread, jlawmi, did you found a solution? was a jira issue created?

here is my mapping:

<hibernate-mapping>
<class
name="mx.connecto.store.Path"
table="Paths"
dynamic-update="false"
dynamic-insert="false"
>
<composite-id name="identifier" class="mx.connecto.store.PathId">
<key-property name="context" column="context"/>
<key-property name="token" column="token"/>
</composite-id>
<set
name="entries"
lazy="false"
inverse="false"
cascade="none"
sort="unsorted"
order-by="identifier"
>

<key>
<column name="context"/>
<column name="token"/>
</key>

<one-to-many
class="mx.connecto.store.ElementEntry"/>
</set>

</class>

</hibernate-mapping>

i would appreciate any help about this issue,

Hi,

I really would like to know what happend to this issue, because I'm experiencing the same problem. I am using hibernate 2.1.4 and jakarta commons for building hashCode and equals methods. I have already tryed everything emmanuel suggested and haven't been successfull.

Here's my mapping:



I would really appreciate your help.

I finally solved the problem. Thanks a lot!

The cause was indeed the implementation of the "equals" method. I was relying on a plugin called commonclipse that can generate toString(), equals(), hashCode() and compareTo() methods using the Jakarta Commons Lang package.

What I haven't notice, is that the code generated by this plugin for the equals method first calls super.equals(). When a class inherits directly from object, this call must be deleted, for the implementation of equals in Object is a pointer comparison (o1 == o2).



I hope this can help the other guys having similar problems.