I have a Hibernate2 application that uses the Interceptor interface to track changes to data in an audit trail. (The audit trail records both the before and after value of an object for each audit event.)

The javadoc for the Interceptor interface makes it clear that "the session may not be invoked from a callback (nor may a callback cause a collection or proxy to be lazily initialized)."

I've been able to avoid this situation because
1) A seperate Hibernate session is used to save the audit objects to the database.
2) All collections that are audited in this app are mapped as collections of entities instead of collections of values (the entities in these collections have there own lifecycle and so they will each get there turn in the Interceptor). As I iterate over the properties of an entity in the interceptor I can skip over any where isPersistentCollectionType() is true.
3) All proxied objects in this particular app have, by circumstance, not required auditing .... that is until now.

If I were to reference an uninitialized before value of a proxied object in the interceptor, I would be violating the restriction specified in the javadoc.

So, now to my question:
Is there a way to obtain the uninitialized previous value of a proxied object (or lazily loaded collection for that matter) in an Interceptor callback without violating this restriction? Has anyone encountered this same problem and found a solution?

Does the event interface framework in Hibernate3 provide a different way to do this?

Regards,
-Jay

An uninitialized proxy, by definition, cannot be modified in terms of its persistent state. Why would you need to audit it?


No idea what you are asking here.

If uninitialized proxied object is updated without first referencing the current value, the previous value that Hibernate saved off and provides to the Interceptor as the previous value will be uninitialized.

Consider:



Then somewhere in application code:





Now in the interceptor, if I try reference the previous (uninitialized) value of status in this foo object, it will cause it to be initialized which, in an interceptor callback, is not allowed.

The proxy for Status is not initialized until you access a property of the Status class itself (other than the id getter, and potentially equals/hashCode).

So I am not really at all understanding the issue here.

Initially you have a proxy for Status(id=1), later you overwrite that with a newly instantiated Status. Why in the world would you need to compare the *state* of the original proxy with the new instance?

I would like to obtain the previous value to record in the audit trail. If this property was not referenced before it was set the previous value is not initialized. Referencing it in the Interceptor callback (in the previousState array) would then cause it to be initialized which the Interceptor's javadoc says is prohibited.

I guess I'm not explaining this very well. What it boils down to is that I have a need to obtain the previous value of a uninitialized proxy in an Interceptor callback. Is there a way to do this that doesn't violate the restriction dictated in the Interceptor javadoc?

Interestingly enough, in my contrived sample code the referencing of this uninitialized proxy in the Interceptor seems to work. Maybe I don't understand the restriction in the javadoc?