I am working with a brownfield database and am trying to configure a subclass map which joins to its subclasses with a column other than that of the specified id. The login table has a primary key column login_sk which I'd like to use as its id. It joins to two tables via a login_cust_id column (to make things more fun the corresponding columns in the adjoining tables are named differently). If I setup login_cust_id as the id of the UserMap it joins to its subclasses as expected. For what I hope are obvious reasons I do not want to use login_cust_id as the id for my User objects.
public class UserMap : ClassMap<IUser>
{
public UserMap()
{
Table("login");
Id(x => x.Id).Column("login_sk"); // want to setup map like this
// if used instead this works for subclass joining / mapping
// Id(x => x.Id).Column("login_cust_id");
// would prefer to only reference login_cust_id for subclass mapping
}
}
public class CustomerUserMap : SubclassMap<CustomerUser>
{
public CustomerUserMap()
{
Table("customer");
Map(c => c.DisplayName, "cust_mail_name");
Map(c => c.RecordChangeName, "cust_lookup_name");
KeyColumn("cust_id");
}
}
public class EntityUserMap : SubclassMap<EntityUser>
{
public EntityUserMap()
{
Table("entity");
Map(c => c.DisplayName, "entity_name");
KeyColumn("entity_id");
}
}
What I'd like to do is only use the login_cust_id column when joining to subclasses. Is there a fluent mapping setting that allows me to specify this? If not a fluent mapping is there a regular NHibernate XML mapping that would work? I'd prefer to not even map the column and only use it for joining if possible. If it helps there is a potential discriminator column login_holder_type which indicates which table to join to.
It did occur to me to setup an IClassConvention but after poking at the passed IClassInstance I could not determine any settings which would help me.
public class UserIdConvention : IClassConvention, IClassConventionAcceptance
{
public void Apply(IClassInstance instance)
{
// do something awesome with instance.Subclasses to
// specify the use of login_cust_id for subclass joining...
}
public void Accept(IAcceptanceCriteria<IClassInspector> criteria)
{
criteria.Expect(x => typeof(User).Equals(x.EntityType));
}
}
The lack of a populated Subclasses collection for the passed instance caused me to look for a more specific inspector which IParentInspector appears to be. Unfortunately Fluent NHibernate does not appear to have corresponding implementations for IParentInstance, IParentConvention or IParentConventionAcceptance like it does for IJoinedSubclassInspector. While I could probably implement my own before I do I wanted to ensure I wasn't barking up the wrong tree.
Is this sort of subclass id adjustment even possible? Am I missing something obvious in either my map or the Fluent NHibernate Conventions namespace? How can I map to a joined subclass with a different column/property than the id of parent?
