Hello, I'v got this scenario in my aplication. I load object from DB (through hibernate) and now I want to do some operation above this object, like change his state (atributes) etc. And then when I call method Save() everything is saved to DB otherwise I don't want to do anything (then I reload this oj from DB and obtain previous state of attributes of object).

How to do that? Because when I change any attribute(property) persisted object then Hibernate automatically save this changes to DB - how to remove object from persistent state (and prevent NHibernate to save it to DB automatically) for a while and after some operation to load it back?

Thx a lot for your answer.

What you want is called evicting object.
On the ISession there is a method Evict() that you can use for this.

Thanks a lot. But I still have same problem. Which command can cause loading of object back to hibernate cache (opposite of Evict() cmd) ?
Strange is that only some attributes of my object are saved into DB and on other hand some don't (although they are changed [in memory]).

The opposite is Lock() or Update(). The difference between them is that Lock() will not make an update to the database, but both of them bring the object back to the session cache.

When you evict/update/save/delete something it will only go as far as you specified by the cascading property in the mapping file.

Consider also using SaveOrUpdate() and SaveOrUpdateCopy if

1) The disconnected tier may send a NEW object back, eg. a object that was not extracted from the store
NHibernate is smart enough to know (based on usaved-value="" in mapping) if the object is to be saved or updated
Another one is to use version control or timestamps

SaveOrUpdateCopy() goes further : reconnect the object, look if has to be updated or saved and...if you have an instance loaded in the CURRENT (say it, Business Facade tier) session, that one wil be automatically updated (in memory!!)

NHibernate is great :-)

hi

you don't need to remove it from nhibernate session

you can just do this after you change attribute

session.Refresh(Object);

and the object is refreshed from database

and return as it was.