Issue with Nullable field

graphicsxp · **Joined:** Thu Aug 14, 2008 5:31 pm **Posts:** 20

Hi,

I have read online:

Quote:

If you want to use NHibernate with .Net 2.0 Nullable Types (int?, DateTime?, etc), all you need to do is to specify full type name of the (non nullable) property.
So, if you've something like "DateTime? DueDate { get; set; }", the mapping will looks something like this: "<propery name='DueDate' type='System.DateTime'/>"
You don't need to do anything else.

Here is my problem now. I have mapped a database table [Cutting], which amongst other fields has got one called 'ClientID'. Now I am trying to load an Entity from another database which have the same [Cutting] table as the one used to configure Nhibernate BUT with the 'ClientID' field missing.

However because it is marked as nullable in my Entity class, it should not cause any harm. But when I call :

Code:

_session.Get<Cutting>(cuttingId);

I get the following exception :

Quote:

could not load an entity. Invalid column name 'ClientID'.

This is how I mapped my ClientID field in the hbm.xml file :

Quote:

What am doing wrong here ?

Thanks

graphicsxp · **Joined:** Thu Aug 14, 2008 5:31 pm **Posts:** 20

Actually thinking about it... My field is missing so the fact that it's nullable is irrelevant.

Therefore, is there a way of ignoring this field when NHibernate queries the table ?

wolli · **Posted:** Wed Sep 24, 2008 6:57 am

Hmm ... you can try and define a sub-class of Cutting which you use for the main db and the base class for the other db.
Or maybe you can try and use a formula on the ClientId property. The formula then would have to check if the colum ist there and return the value or null if not (don't know if that is possible with SQL).
Or you can define a view on the table in the other db which has a clientid column which contains null.

graphicsxp · **Joined:** Thu Aug 14, 2008 5:31 pm **Posts:** 20

I think you are right regarding the Views. That should be the way to go.

But thinking about it, all my client databases should be exactely the same so I'm just going to normalise them, and that will solve the problem.

Thanks