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I have a need to generate a unique integer which I use to identify an order to an external system. I'm using the NHibernate HiLo generator in the application, so can I access the generator programmatically to get it to return me a unique integer? I don't need to store this in any database key. I just want to use the NH functionality of generating unique integers.

I'd add a column to the HiLo table that I'd only use for this unique number sequence and not for any real database key. For example, say I added a column "Foo" to the hibernate_unique_key table.

Could I then do something to the effect:

int n = GetNextId("Foo");

Where I just pass the name of the column?

Mike Scott
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1 Answers1

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You should be able to just instantiate TableHiLoGenerator or SequenceHiLoGenerator, configure it and call Generate when you need a value.

When calling Generate(), you can pass session.GetSessionImplementation() for the first parameter and null for the second one.

Now, keep in mind that, if you aren't really storing these numbers, it might not be the best idea to use the DB to generate them. GUIDs are effectively unique, 128-bit numbers that can be generated more easily.

Diego Mijelshon
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  • Diego, I'm looking into doing this but it's not intuitive how to supply the various parameters, e.g. the Dialect parameter of the contructor of TableHiLoGenerator, the ISessionImplementor parameter of the Generate method - and what's the obj parameter of the Generate method? – Mike Scott Dec 19 '12 at 22:16
  • Those would be the dialect you're using, and `session.GetSessionImplementation()`. I think `obj` is not used. – Diego Mijelshon Dec 20 '12 at 03:31
  • Diego, I eventually figured out where to get the dialect, you can cast the session into ISessionImplementor and that obj can be null, as you said. However, all this is non-trivial and your answer doesn't give enough detail for me to mark it as the answer. I could answer myself with all the details but I thought I'd give you a chance to edit your answer and fill it out, if you wish. – Mike Scott Dec 25 '12 at 13:26
  • Diego, sorry to be a pain but calling the Configure() method isn't trivial - it's not obvious what the first type parameter should be, what the dictionary parms are and where to get the dialect. This really needs an example to be clear and complete. – Mike Scott Dec 25 '12 at 15:55