Question

We use one (read-only) session which we disconnect as soon as we retrieve the data from the database. The data retrieved, often has lazy-loaded properties which are not initialized yet.

When we try to access the properties, the following exception gets thrown:

NHibernate.LazyInitializationException

Initializing[NHibernateTest.AppUser#16]-failed to lazily initialize a collection of role: NHibernateTest.AppUser.Permissions, session is disconnected

Is there a way (interceptor) to automatically detect that the application is trying to access an uninitialized property, so that the interceptor can quickly open the connection and close it after the unit of work?

Fetching everything at once would nullify the usage of laziness.

Answer 1

There is no efficient way to do that. The idea is that you keep the session open until your done with the session. There should be one session per unit of work. (a session is kind of unit of work actually).

Fetching everything your need in one query is more efficient than fetching everything you need in multiple queries, so I don’t agree with your last statement. Lazy loading is useful for lazy programmers (like me) but is never more efficient than eager loading. Lazy loading can save you some programming time, but you still have to watch out for to many queries being executed (select N+1)