Hi all,

My client is editing values in the database directly and not seeing the changes show up; I think this is because NHibernate is caching the old values. What's the recommended best-practise in this situation, and how can I clear the cache easily?

Hi,

If you mean NHibernate is holding a copy in the session's first-level cache, then simply calling ISession.Clear() should do the trick; then re-load your objects.

You might want to call ISession.Flush() first to flush out any changes you've made using NHibernate first.


Regards,
Richard

The problem is, how do you do this abstractly? I.e. how can you find out what it actually in the first level session cache in order to reload it? I guess you can do a flush and implement IInterceptor.PreFlush() to remember the list of what's in the cache, since that appears to be the only place where the 1st level cache contents are exposed. Then after the flush, get that list from your implementation of IInterceptor and reload everything by its ID. But that's kind of lame way to get the cache contents ...

ramsay,

Although updating the database by means other than Hibernate is not recommended, a query.list() should give you the freshest data, no matter what, because it always executes a query to the database.
Caching only works with session.load (id) retrievals.

The session usually provides a first level of "caching". In Hibernate the caching proper is called "second-level-cache", for this reason.
If you want to completely erase objects or object' collections from the cache, you call session.evict(<the object or collection>).

gonazao is correct, except if you're also using the query cache for your query in which case the objects in the object cache will be returned if the same query is executed twice.

Symon.

Thanks for this. I've looked into it further after taking your comments on board and resolved the problem. This link also helped:

http://www.hibernate.org/hib_docs/nhibe ... ssioncache

Cheers!