NHibernate如何在IEntity上更新ID

Question

I have a row in my DB w/ Id = '00000000-0000-0000-0000-000000000000',

how can I force update this Id using session/transaction ,basically assign a valid Id to the row.

I've tried:

var testrow  = repo.get(id);
testrow.Id = Guid.NewGuid();
repo.UpdateRow(testRow);

---

My update repository update method:

public void UpdateRow(TestRow row)
        {
            using (ISession session = _sessionFactory.OpenSession())
            using (ITransaction transaction = session.BeginTransaction())
            {
                session.Update(row);
                transaction.Commit();
            }
        }

---

I get the error:

"Row was updated or deleted by another transaction"

If I attempt to delete the object using :

session.delete(row) 
transaction.Commit();

I get the following error:

Unexpected row count: 3; expected: 1

---

There are 3 rows each with a unique Id, one happens to have an incorrect Id of 00000000-0000-0000-0000-000000000000'

Answer 1

An id must never change, this an error in your application design. Delete the old entity and recreate with the new values.

Answer 2

I think you have not 1 row with that id - but three. Try using a DB-tool and do a regular select * from [table] where id = '00000000-0000-0000-0000-000000000000' - I'll bet that is your problem. That would give the unexpected error - and for the love of all that is good - have a unique constraint on you id-column :-).

Also, your update method violates the unit of work pattern that is ISession. You load the object in one session, update it - and then try to make the update in another session - that is bound to give you unexpected results!

Always make this kind of work in one ISession!

EDIT: By the way - nHibernate cannot update your Id - that is how nHibernate knows which object you are holding! It simply doesn't make sense what you are doing. If you really need to update that row - use a DB-tool and do it manually (and take measures so it cannot happen again...)

EDIT2: To correct the problem, use this in code: nHibernate supports raw sql - use ISession.CreateSQLQuery("DELETE FROM [table] WHERE Id = '00000000-0000-0000-0000-000000000000'").ExecuteUpdate();