fluent nhibernate auto increment non key (Id) property

Question

Is it possible to have an integer property of a class auto increment managed by the database but not be a primary key (or Id as NHibernate refers to them)? I'm having trouble finding examples of how to do this. Any help would be appreciated. Thanks.

Answer 1

Two options.

• if the database is 100% responsible for this you just need to tell NHibernate that the property is generated and not to include it in any updates/isnerts. The downside is that NH will need to do an additional select to keep the value fresh in memory.

  < property name="Foo" generated="always" update="false" insert="false" />

• if the database is not responsible and you just want to have this done automatically you can use an interceptor to set the value to 1 on an insert and to increment it by 1 on an update.

http://www.nhforge.org/doc/nh/en/index.html#objectstate-interceptors (11.1 - Interceptors)

You would override OnSave() to find the property and set the initial value and then override OnFlushDirty() to find the property property and increment.

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Edit:

I'm an idiot, didn't notice you said Fluent NHibernate.

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Edit #2:

I think you might also be interested in using this column as a versioning?

< version name="Foo" generated="always" />