Question

I’m using Fluent NHibernate to map my entities and I’ve come to a set that I’m having probelsm gettting mapped. I’ve tried different variations of SubclassMap but I can’t seem to get Cart, Project or Order mapped correctly. Item, CartItem, OrderItem and ProjectItem map fine. I’m fairly new to NHibernate and I just can’t figure out how to tell it to do what I want.

EDIT: This is the schema I’m going for with this inheritance structure:

public abstract class Item
{
    public virtual int Id {get;set;}
    public virtual decimal Price {get;set;}
}

public class CartItem : Item
{
    public virtual string ProjectName {get;set;}
}

public class OrderItem : Item
{
    public virtual IList<Payment> Payments {get;set;}
}

public class ProjectItem : Item
{
    public virtual string ProjectName {get;set;}
}

public abstract class ItemCollection<T> where T: Item
{
    public virutal IList<T> Items {get;set;}
}

public abstract class CommerceCollection<T> : ItemCollection<T> where T : Item
{
    public virtual decimal Total {get;set;}
}

public class Project : ItemCollection<ProjectItem> 
{
    public virtual string ProjectName {get;set;}
}

public class Cart : CommerceCollection<CartItem> {}

public class Order : CommerceCollection<OrderItem>
{
    public virtual string OrderTrackingNumber {get;set;}
}

/*-------  MAPS  -------*/
public class ItemMap: ClassMap<Item>
{
    public ItemMap()
    {
        MapId();
        Map(x=> x.Price);
    }
}

public class OrderItemMap : SubclassMap<OrderItem>
{
    public OrderItemMap()
    {
        Map(x => x.OrderItemProperty);
    }
}

public class CartItemMap : SubclassMap<CartItem>
{
    public CartItemMap()
    {
        Map(x => x.CartItemProperty);
    }
}

public class ProjectItemMap : SubclassMap<ProjectItem>
{
    public ProjectItemMap()
    {
        Map(x => x.ProjectItemProperty);
    }
}

 public class CartMap : ClassMap<Cart>
    {
        public CartMap()
        {
            Map(x => x.Total);
            HasMany(x => x.Items);
        }
    } 

    public class OrderMap : ClassMap<Order>
    {
        public OrderMap()
        {
            Map(x => x.Total);
            HasMany(x => x.Items);
        }
    }

Answer 1

I figured out what I needed to do. For the classes that implemented the generic base class (CommerceCollection) I had to add a map for the generic collection with it’s argument and then specify the KeyColumn property on the subclass.

Here is the new CartMap:

public class CartCollectionMap : CommerceCollectionMap<CartItem> {}

    public class CartMap: SubclassMap<Cart>
    {
        public CartMap()
        {
            KeyColumn("CommerceCollection_id");
        }
    } 

Nhibernate was generating SQL like below which would fail on the ‘ in the column name.

CREATE TABLE Cart (CommerceCollection'1_id int PRIMARY KEY)