On 13/07/2011 21:14, Pinaki Poddar wrote:
Yes. Any audit facility needs to have a snapshot of the entity when it
entered a persistence context, so at @PreUpdate or at any other time points,
it can figure out what has essentially been changed about that entity in a
transaction. Now either one can build their own mechanics to store the
original state of the entity or can use OpenJPA's own facility to access the
original state. The blog article showed the later approach.
I also went with using the OpenJPA stored version of the original object.
There are a few niggles to getting that data that one has to work with,
but I still think it's considerably less effort than building your own
mechanism.
Secondly, in my view, an audit facility should be orthogonal. The actual
domain entity need not know that it is being audited. Thereby, the domain
entity need not have an association or knowledge of an Audit object.
I'd agree with that for a general purpose audit facility.
In my case I don't even call it "audit" it's change tracking, and the
change information is displayed alongside the entities in the most
common cases.
Thirdly, the audit facility should allow the audit information be stored in
a separate database, in the same database or may even be logged in a file.
That is to say that persistence of audit information should be decoupled
from persistence of the domain objects.
Again, true for a general purpose audit facility.
If you want to be really secure the audit log should be sent directly to
a printer :)
If you intend to store audit information as a persistent entity in the same
database as the domain entity, then the simple solution is something like
this in a domain class:
@PreUpdate
public void audit() {
Audit audit = new Audit();
// now populate audit information
// .... some serious delta computation
// Now get the entity manager that is managing this current domain
object
OpenJPAEntityManager em =
OpenJPAPersistence.getEntityManager(this);
// And persist the audit information in the same transaction
em.persist(audit);
}
I wonder if that bends the rules any more than my approach?
Jim
