how to update detailsview's dropdown field before item inserted?

Hi,

I am using EF6.0 and .net 4.5.  Details view is bound to a EF. I have many dropdown fields and they all are bound field. I would like to change value of one of the dropdown ( say "Drp_ELIG") manually before item is inserted or updated to database.

I am trying to update value on onItemInserting method of DetailsView but it is not updating.

It inserts what it displayed on the page but not what I am updating on onItemInserting method.

If I do not BIND my ("Drp_Elig") it gives error. so I must bind also? it can't let me use Eval.

Please help

JRS