Hi,

I am fairly new to Hibernate and am trying to develop a Swing application using Hibernate 3 to persist my domain objects. I am trying to design my application using "best practices" i.e. making sure there is a clean separation of layers etc.

My question relates to Lazy Initialisation of collections. I keep hitting a LazyInitializationException - I understand why - I am closing the session before accessing a collection that is lazily loaded. The question I have is where should I open and close the session. Also, I have a problem with having to open the session just because I have a collection that is lazily loaded. Surely there must be some way of automagically opening the correct session when I access the lazily loaded collection.

Sorry for not posting anything specific - I suppose this is a general design question. Thanks for all your hard work.

Malcolm

Mmm - sounds like you want to use Application Transactions where you keep the Hibernate session open till a logical user transaction completes. This will probably influence the way you design your Swing app as well - in terms of walking the user through a defined set of use-cases rather than allow him to skip around in a more random way.
You can find more information about application transactions both on the website and in the book (HIA, Manning Press).
HTH
Satish

PS Alternatively, you could initialise proxies (both single-valued entities and collections) explicitly as needed using Hibernate.initialize(...) and/or use detached objects...

Thanks for your input. I have done lots of Googling on this issue and it sounds as if the various Session strategies for web based applications are well thought out - alas, not for Swing apps.

I think that I am going to have to write a business facade and instead of calling foo.getBars() I will have to know that bars are lazily instantiated and so call BusinessFacade.getBars(foo). BusinessFacade.getBars(foo) will attach back to the session and initialise the collection.

Not the most ideal solution - but what is :-)

Cheers

Malcolm