CODEWITHSUNDEEP
c#nhibernatesessionlazy-loading
Piere
Piere

Reputation: 83

NHibernate Lazy Loading - After the session closes

Is it possible to lazy load a related object during an open session but to still have the related object available after the session closes?

For example, we have a USER class and a related ROLE class. When we load a USER we also lazy load the related ROLE object. Can we have the USER and ROLE class fully loaded and available after the session is closed?

Is this functionality possible?

Upvotes: 5

Views: 3601

Answers (3)

Jamie Ide
Jamie Ide

Reputation: 49261

Yes. Once the session is closed, any objects that were lazy-loaded will remain in memory and you can access them without any problems.

Upvotes: 0

Steve Py
Steve Py

Reputation: 34783

If you're dealing with a 1-1 relationship (0-1 role per user) then possibly the simplest option would be to configure it for eager fetching it rather than lazy loading. Lazy loading is really geared towards 1-* relatives, or objects that are particularly large and rarely needed. NH does a pretty fine job of optimizing queries to include eager data fast in scenarios like that.

Upvotes: 0

KeithS
KeithS

Reputation: 71573

Short answer: no. You must initialize anything you will need after the session closes, before closing the session. The method to use to force loading a lazy proxy (without enumerating it) is NHibernateUtil.Initialize(USER.ROLES).

Long answer... kind of. It is possible to "reattach" objects to a new session, thereby allowing PersistentBags and other NH proxies to be initialized. The best method to use, given that you know the object exists in the DB but not in your new session, and that you haven't yet modified it, is Session.Lock(USER, LockMode.None). This will associate the object with the new session without telling NHibernate to do anything regarding reads or writes of the object.

HOWEVER, be advised that this is a code smell. If you are regularly reattaching objects to new sessions, it is a sign that you are not keeping sessions open long enough. There is no problem with opening one session per windows form, for instance, and keeping it open as long as the form is open, PROVIDED you close it when the window closes.

Upvotes: 9

Related Questions