Property which should be a readonly db-field (Fluent NHibernate Automapping) - nhibernate

Question

Im using the Fluent NHibernate together with the automapping functionality. Now im lookin' for something like a configuration, setting, custom attribute - whatever - to declare an entity property as "ReadOnlyFromDb"
In the MsSql database im using a computed column in one of my tables where a value is calculated depending on some other values of the specific data row. Now I have declared this column in the entity class as
public virtual int STATUS { get; private set; }
On getting the specific data of the table everything works fine. The property STATUS is filled correct with the specific value in the datatable.
The problem occures when i try to SaveUpdate() the specific object.
I always get the exception
A computed column cannot be the target of an INSERT or UPDATE statement
Which is correct for my understanding - and its how it was supposed to be ;)!
Basically im looking for a configuration, setting, custom attribute - whatever - to say
Hey Fluent NHibernate - get the specific property propertyName but do not insert / update the property propertyName
Is there something like that? Or does a workaround exists for this case?
I've searched the fluent nhibernate wiki but have not found a smilliar case.
I hope that someone has already faced and solved this problem!
Here is the code snippet how I create the session (maybe it helps):
public static ISessionFactory GetNHibernateSession()
{
if (nhibernateSession != null)
return nhibernateSession;
if (ConfigurationManager.AppSettings[msSqlConnectionString] == null || ConfigurationManager.AppSettings[msSqlConnectionString] == String.Empty)
throw new NullReferenceException(String.Format("AppSetting '{0}' must not be null!", msSqlConnectionString));
//nhibernateSession = Fluently.Configure().Database(MsSqlConfiguration.MsSql2005.ConnectionString(ConfigurationManager.AppSettings[msSqlConnectionString]))
// .Mappings(m => m.AutoMappings.Add(AutoMap.AssemblyOf<T_ABWEICHUNGEN>().IgnoreBase<BaseClass>)).BuildSessionFactory();
nhibernateSession = Fluently.Configure().Database(MsSqlConfiguration.MsSql2005.ConnectionString(ConfigurationManager.AppSettings[msSqlConnectionString]))
.Mappings(m => m.AutoMappings.Add(AutoMap.Assembly(System.Reflection.Assembly.GetExecutingAssembly())
.Override<T_ABWEICHUNGEN>(map =>map.Map(d => d.A08_STATUS_FILE).Length(2147483647))
.IgnoreBase(typeof(BaseClass))
.IgnoreBase(typeof(IDColumn))
.IgnoreBase(typeof(MsSqlQuery))
.IgnoreBase(typeof(MsSqlParamCollection))
.IgnoreBase(typeof(AbweichungStatus))
)).BuildSessionFactory();
return nhibernateSession;
}
}
thanks so far for the response - helped me so far.
But - is there a way to get this solved more 'dynamicly'?
For example:
I want to declare a custom attribute called [ReadOnlyDbField] now declare all properties of the entity with this cusomt attribute to say: Just read this value and do not update / insert it.
Basically i want to say in the configuration
Map all properties with the custom attribute [ReadOnlyDbField] to Not.Insert().Not.Update()
Is there a way to implement this?

Answer 1

.Override<Entity>(map => map.Map(d => d.STATUS).Not.Insert().Not.Update())
update: account for edited question
public class ReadonlyDbFielConvention : AttributePropertyConvention<ReadOnlyDbField>
{
protected override void Apply(ReadOnlyDbField attribute, IPropertyInstance instance)
{
instance.Not.Insert();
instance.Not.Update();
}
}