Hi
I am trying to use the TableHiLoGenerator to generate a id *but* store it as as a string in the Table. Unfortunately, I am working on a legacy database where the row_id is a string. Ideally, I would like to use the TableHiLoGenerator and use type conversion (IUserType?) and add a prefix. For eg: if the id returned is (int)23, I would like to convert it to "1-00023" where "1" is the prefix and "-" is the seperator.

First things fist, I just wanted to see if the TableHiLoGenerator could store the id as a string and I ran into a road block

Here is the relevent mapping

<id name="Id" column="ROW_ID" type="string" unsaved-value="0">
<generator class="hilo">
<param name="table">hi_value</param>
<param name="column">next_value</param>
<param name="max_lo">100</param>
</generator>
</id>

The exception I got was

{"The type initializer for 'NHibernateRepository.Repository' threw an exception."}

and the inner Exception is

{"type is not a ValueTypeType\r\nParameter name: type"}

Looks like I cannot use the TableHiLoGenerator to generate an Int and put it as a string into the ROW_ID column thru automatic conversion.

Any idea how to implement a prefixed string id generator using TableHiLo algorithm?
Thanks
arkae

You gonna need to extend the NHibernate.Id.TableHiLoGenerator class.
Take a look, this it's the class, the exception thorws because it make a conversion thinking that you string, is a numeric representation.
https://nhibernate.svn.sourceforge.net/svnroot/nhibernate/trunk/nhibernate/src/NHibernate/Id/TableHiLoGenerator.cs

Extend this type a make you own generator.

I'm porting Hibernate Shards, and I need to deal with a similar problem, I need to insert a Id, into a Guid, for example
If I generate this Guid:
3F2504E0-4F89-11D3-9A0C-0305E82C3301
I must convert it to
000D04E0-4F89-11D3-9A0C-0305E82C3301
This mean that the prefix is the number 13 (000D at hex)

This it's the implementation that I propouse:
https://nhibernate.svn.sourceforge.net/svnroot/nhibernate/trunk/nhibernate/src/NHibernate.Shards/src/NHibernate.Shards/Id/ShardedUUIDGenerator.cs

Best regards.