I have a few objects in my framework that have calculated properties (i.e. properties that are not persisted to my data store and are calculated based on other properties of the object). I don't want to flag these properties as virtual (mainly because I don't want some developer coming along later and attempting to override them); however these properties must be public. I'm not including them in the my mapping file (since there is nothing in the data store to map them to) but if I don't flag them as virtual NHibernate still throws an exception ("The following types may not be used as proxies"). Is there a way to override this behavior?

Thanks

You have to make them virtual because otherwise an uninitialized proxy won't know to initialize when the property is touched.

Even worse, we have some non-persisted properties that get assigned through our implementation of IInterceptor.Instantiate(). E.g. we assign a business rule object here that listens to property changes and reacts accordingly, because we don't want our entity classes to know about business rule classes directly (our entities only know the rule interface, which only exposes a method for the entity's ToString() method to call). The problem is that IInterceptor.Instantiate() does not get called when a a proxy is first created, but only when the proxy is initialized. So, when we initially tried to make these non-persisted properties non-virtual (because we didn't want reading the property to trigger initializing the proxy), the property would incorrectly return null because it was never initialized by the interceptor. We were forced to make these properties virtual to get the correct behavior.

AFAIK you could disable lasy load of a class, forcing nhibernate to create all that is selected in a list.