Many To One/Reference property as Discriminator

[Johnny Alibuyog]

Hi All,

Is there any possible way to use a mapped many-to-one property as discriminator.
My mapping looks like this

     Reference(x => x.BusinessType);

     DiscriminateSubClassesOnColumn("BusinessTypeId")

          .AlwaysSelectWithValue()
          .Length(3);

It generated the right table with the association but when saving, I encounter exception "Invalid Index 8 for this SqlParameterCollection with...".
I believe it is generating duplicate mapping for "BusinessTypeId".

Thank you in advance.

Best Regards,
Johnny

[Trinition]

I'm having this same trouble.  Did you ever find a solution?  This StackOverflow post suggests using a formula: 
http://stackoverflow.com/questions/3426477/nhibernate-using-a-discriminator-column-as-a-many-to-one-relationship 

[Trinition]

FWIW, that StackOverflow article solved it for me -- use a formula that is just the many-to-one's column,