1 table = 1 class + 1 one of 2 abstract class

Question

Hi

I have two tables which looks something like this

Table Queue
 int ID;
 string Name;
 int MessageID;
 string To
 string From
 string Topic
 string Email

Table Message
 int ID
 int MessageType

This is a rather simplified version, but what we did in the classes was to create 1 class named

 class Queue
 int ID
 string Name
 Message message

And then we have an abstract message with either types of message.

 class abstract Message()

 class SMSMessage : Message
 string ToMobile
 string FromMobile
 string Message

 class EmailMessage
 string ToEmail
 string FromEmail
 string Topic
 string Email

However now my problem is figuring out how to map this with fluent Nhibernate. How would i do this ?

Answer 1

I could rewrite the article, but I think I'll allow it to stand on its own: http://marekblotny.blogspot.com/2009/03/fluent-nhibernate-and-inheritance.html

EDIT:

Running with the spirit of the article, I'd try the following (and I really have no idea if this will work):

Write a Message map:

public class MessageMap : ClassMap<Message> {
  public MessageMap() {
    Id(x=>x.Id).GeneratedBy.Native();
    // only the common stuff

    DiscriminateSubClassesOnColumn<int>("MessageType")
      .SubClass<SMSMessage>(1, m=>m.HasOne( x=>{
                                                 Map(x=>x.ToMobile);
                                                 Map(x=>x.FromMobile);
                                                 // etc
                                               })
                            .Cascade.SaveUpdate()
                            .FetchType.Join())
      .SubClass<EmailMessage>(2, m=>m.HasOne(x=>{
                                                 Map(x=>x.ToEmail);
                                                 Map(x=>x.FromEmail);
                                                 // etc
                                               })
                            .Cascade.SaveUpdate()
                            .FetchType.Join())
  }
}

We'll do SMS only for now ...

public class SMSMessage : Message {
  public virtual string ToMobile { get; set; }
  public virtual string FromMobile { get; set; }
  ...
}

Here's the mapping class...

public class SMSMessageMap : ClassMap<SMSMessage> {
  public SMSMessageMap() {
    WithTable("Queue");
    Id(x=>x.Id, "QueueID").GeneratedBy.Foreign("Message");
    Map(x=>x.ToMobile, "To");
    Map(x=>x.FromMobile, "From");
    WithTable("Message", m=>
    {
      m.Map(x=>x.MessageBody);
    });
  }
}