Creating class hierarchy mappings

It's common to have an inheritance hierarchy of subclasses. In this example, we will show you one method for mapping inheritance with NHibernate, called table-per-class hierarchy.

Getting ready

Complete the previous Mapping a class with XML example.

How to do it…

1. Create a new class named Book with the following code:

   namespace Eg.Core
   {
     public class Book : Product
     {
   
       public virtual string ISBN { get; set; }
       public virtual string Author { get; set; }
   
     }
   }

2. Create a new class named Movie with the following code:

   namespace Eg.Core
   {
     public class Movie : Product 
     {
   
       public virtual string Director { get; set; }
   
     }
   }

3. Change the Product mapping to match the XML shown in the following code:

   <?xml version="1.0" encoding="utf-8" ?>
   <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
       assembly="Eg.Core"
       namespace="Eg.Core">
     <class name="Product">
     ...