Hi,

I am using managed versioning (with a numeric version), and when I create a new object, NH persists it to the database with an initial version number of zero (because Int32Type.Seed returns 0).

The issue I have come across is that when I was using either or in my mapping file, this caused a crash when I updated the object and tried to re-persist it. This is because NH interpreted the version number of 0 as being unsaved and therefore tried to create another record with the same primary key.

The only way I could get my app to work is to set unsaved-value="-1" and to initialise the version number of every object to -1 before persisting it.

So my question is: why does the Hibernate In Action book give examples of mapping files with when this will not allow you to update a previously persisted object?

IMHO, the problem would be neatly solved if NH made the initial version 1 instead of zero, as this would allow unsaved-value="0" to work and would remove the requirement to set the version number to -1 in the object itself.

This comes as a result of porting from Java where they can use nullable Integers for versions, instead of just ints. I'm not sure I should change the seed in the stable version, it would be a breaking change.

Sergey, thanks for the explanation.

I guess that's the risk of using a book about Hibernate and not NHibernate. I agree that you should not change the value of Int32Type.seed, as that is likely to create other problems.

As a possible solution, perhaps 1 could be added to the initial seed number in NHibernate.Engine.Versioning.Seed? As the HIA book says