用fluent nhibernate映射父表和子表

嗨,在我的数据库中定义了以下表:

Transactions:
- TransactionID (PK, Identity)
- TypeID (FK)
- Amount

TransactionTypes:
- TypeID (PK, Identity)
- Type

ProductTransactions:
- TransactionID (PK)
- Discount

有两种类型的事务(事件和产品)。产品具有附加折扣字段,因此定义了附加表。

我现在有以下实体:

public class Transaction
{
    public virtual int TransactionID { get; private set; }
    public virtual TransactionType Type { get; set; }
    public virtual decimal Amount { get; set; }
}

public class ProductTransaction : Transaction
{
    public virtual decimal Discount { get; set; }
}

public enum TransactionType
{
    Event = 1,
    Product = 1
}

最后,我的映射如下:

public TransactionMap()
{
    Table("Transactions");
    Id(x => x.TransactionID);
    Map(x => x.Amount);
    DiscriminateSubClassesOnColumn("TypeID")
        .SubClass<ProductTransaction>(TransactionType.Product, x => x.References(y => y.Type));
}

public ProductTransactionMap()
{
    Table("ProductTransactions");
    Map(x => x.Discount);
}

我想说以下内容来插入产品交易:

productRepository.Insert(new ProductTransaction { Type = TransactionType.Product, Amount = 100m, Discount = 10m });

但是我的地图有问题。我确信我的问题是围绕distingSubclassesonColumn位的,但是我有点迷失在这里。如果有人能告诉我怎么做,我会非常感激的。谢谢