Hi,
I have many-to-one relation to a class with composite id. While trying to persist, I get this exception:

java.lang.ClassCastException
at net.sf.hibernate.type.ComponentType.isModified(ComponentType.java:420)
at net.sf.hibernate.type.ManyToOneType.isModified(ManyToOneType.java:81)
at net.sf.hibernate.type.TypeFactory.findModified(TypeFactory.java:249)
at net.sf.hibernate.persister.AbstractEntityPersister.findModified(AbstractEntityPersister.java:291)
at net.sf.hibernate.impl.SessionImpl.flushEntity(SessionImpl.java:2532)
at net.sf.hibernate.impl.SessionImpl.flushEntities(SessionImpl.java:2477)
at net.sf.hibernate.impl.SessionImpl.flushEverything(SessionImpl.java:2279)
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2258)
at net.sf.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:61)
at org.springframework.orm.hibernate.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:460)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:373)
at
.....


If I try to debug, the ComponentType.isModified(...) method gets old and current object to compare and they are the same type (instances of the composite ID class). So far it is OK, I think. But why the current values are extracted in different way than the old ones?
Because this is the reason why I get the ClassCastException, I can't cast instance of my composite ID class to Object[].

Shouldn't be the old values extracted like "Object[] oldValues = getPropertyValues(old, session);" instead of "Object[] oldValues = (Object[]) old;".
If I make a new build of Hibernate with this change, everything gets persisted correctly.
So I don't know if this is a bug or if I'm doing something wrong? Maybe mappings are wrong?

This is example of my mappings:

many side:

.....
<many-to-one
name="myPropertyName"
class="OneSideClass"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
>
<column
name="column_1"
/>
<column
name="column_2"
/>
</many-to-one>
.....

one side:

<class
name="OneSideClass"
table="OneSideClassTable"
dynamic-update="false"
dynamic-insert="false"
mutable="false"
>
<composite-id
name="id"
class="composite_ID_class"
unsaved-value="none"
>
<key-property
name="property_1"
type="java.lang.String"
column="column_1"
/>

<key-property
name="property_2"
type="java.lang.String"
column="column_2"
/>

</composite-id>
.....

Thanks for any ideas or comments.

Pavel

It might be that your equals method doesn't first check to see that it's comparing objects of the same type? I've gotten a ClassCastException for that reason but I don't remember the stack trace.

What version of hibernate are you using? I use 2.1 and that line number isn't valid, so that must not be your version. :)

Jenica

It might be that your equals method doesn't first check to see that it's comparing objects of the same type? I've gotten a ClassCastException for that reason but I don't remember the stack trace.

What version of hibernate are you using? I use 2.1 and that line number isn't valid, so that must not be your version. :)

Jenica

Thanks Jenica, but I don't believe it solves my problem. In every equals method I have I check the compared object to be an instance of the same class as this.

Sorry for not stating my Hibernate version - it's 2.1.6.

I found a workaround, the object on many side is used only for reading purposes (mapping with attributes insert="false" and update="false") and then I have two additional getter and setter method to persist both properties of composite ID key. The setters are empty and getters return values from the object. Although it works, I don't really like the solution much, I believe there has to be the way to force the object to persist its composite ID properties itself.

As I see it, the ComponentType.isModified(...) is used for dirty data checking, but I don't know why are old and new values (which are instances of the same class) extracted differently and why the old value is cast to Object[]. I'm really confused how this can work...

Maybe it's really my bug somewhere in mappings or I understand the dirty data checking problem wrong, so I would be grateful for any other ideas.

Thanks,
Pavel

I also got the same exception: ClassCastException.
I'm using Hibernate-Version: 3.1.2

--- description ---

I tried to implement a custom authorization check using a PreUpdate listener and tried to see which fields are changed.
I have a component field (a contained object) that is changed.

The first lines of the stacktrace looks like


...


The method isModified looks like (>>> indicates exception)




And my local variables are:



The componenttype contained object is the ValidPeriodImpl that is successfully transformed to an object array for the current state (currentValues) but the old state (that also is a ValidPeriodImpl) is cast to an object array and therefore causing a classcastexception.

---

I have now changed my code in my eventlistener to use findDirty instead of findModified and it seems to work better! I still get back an array of changed indexes so I think it could be used as a workaround. Maybe?

If someone has another opinion I would gladely read it.