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1.2:

Transaction.commit():

I have a sql server table with a Datetime Column with Allow NULL. I am loading all the records from that table via NHibernate then I iterate through the collection take out my required Record(Object) from that collection, make some changes to it ( I assign value to DateTime field) and then I save and commit this object. All this happens in a single Session.

My problem is that when I commit the transaction I get an exception saying that DateTime should be between 01/01/1700 to 31/12/9999.

When I enabled the logging of SQL queries I found that when I call transaction.commit() it sends updates for all the records in the collection whereas I expected it to only send the updates for the record which I changed. Anyways, as it is sending update for every record in the collection some of them have NULL datetime field and due to which the whole transaction fails.

Following is the algorithm I am using.

Session = CreateSession();
Transaction = Session.BeginTransaction();

Queue = GetQueue(QueueId);
Message m;
foreach( Message m in Queue)
{
If ( Message.status.equals("NEW") )
{
m = Message;
break;
}
}

m.processingTime = DateTime.NOW;

Session.Save(m);
Transaction.Commit();
Session.Close();


I know that whenever we commit a transaction it synchronizes with the database but I expected only changed records to be updated not everything.

Lastly I know that it is not the correct way to do what I have done. I should have a specific HQL query fetching the record directly from database. But I am testing different things so it would help me understand the behaviour.

Help is much appreciated

Thanks
Syed

You don't need the save when the objects are still in the session. If you make an additional Save on a object that is already in the session, normally nothing should happen. But I think in that case it cascades the explicit save to the items and executes the corresponding updates.

I have found the issue. It has nothing to do with save but the problem lies in the fact that C# doesn't allow a NULL DateTime field where as SQL Server allows it.

When we loaded the Collection or Queue object it loaded all the messages in that queue. Some of those messages had empty DateTime column so C# had put default value 01/01/0001 in that field. When I comitted the transaction NHibernate saw that DateTime field had changed for every Message Object and it issued an Update.

See the article below to resolve this issue.

http://www.ayende.com/Blog/archive/2007 ... ssues.aspx

Anyways thank you very much for posting me a reply.

Cheers,
Syed