NH-3342 - Lazy loading of ISet throws exception when no result

[nhibernate-bot]

Stefan Reicht created an issue — 5th December 2012, 12:19:49:

I tried to update NHibernate to 3.3.2 GA from 2.1.2 GA. With 2.1.2 I used ByteCode.Castle as proxy.

During testing I got this error:
Message: "Object reference not set to an instance of an object."
StackTrace: " at NHibernate.Collection.PersistentBag.GetEnumerator() in p:\nhibernate-core\src\NHibernate\Collection\PersistentBag.cs:line 431"

It occures when I try to read from an ISet, which is lazy loaded and there are no results from the database.
I also added a little example (only written with Notepad).

I solved this problem by adding following line in the DefaultInitializeCollectionEventListener, just before the reading from cache/database:
collection.BeforeInitialize(ce.LoadedPersister, 0);

I am not sure if it´s the best solution, but it works for my cases.

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Oskar Berggren added a comment — 5th December 2012, 20:48:41:

I don't have the code at the moment, but I find it a little odd that you get exception from PersistentBag when you are handling an ISet. Is the mapping correct?

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Stefan Reicht added a comment — 6th December 2012, 5:45:49:

With NH 2.1.2 and ByteCode.Castle it worked fine.
Therefore I think its ok.

I forgot to write that I am using an CompositeID for the ISet mapping.
Maybe this is also relevant for solving the problem.