Question

I have been working on my first experimental DDD project. The objective of this project is for me to get a feeling on the whole DDD concept. Oddly enough, as i have read it’s the more difficult part, i find the ubiquitous language “translation” easier than the whole architecture itself, thus my question.

I have only used in my past projects L2S (Linq to SQL). My applications were not DDD per se but they do have a Business Object (aside from the ones that linq to sql generates) and i have a repository for this objects. For example,

public class Customer
    {
       public ID {get; set;}
       public string Fullname {get; set;}
       public Address address {get; set;}
       public List<Invoices> invoices {get; set;}
    }

Now, in L2S, i have to breakdown this class into three different queries and submit them into the database. I have a mapper (extension methods) to make my life “easier”. Something like this.

public void AddCustomer(Customer customer)
{
// This customer i am passing is the business object
// For the sake of demo, i am going to avoid the whole attach(), check for ID, etc.
// I think you are going to get what i am trying to do here.

using{ var context = new L2SContext())
{
context.CustomerEntity.InsertOnSubmit(customer.ToEntity());
context.AddressEntity.InsertOnSubmit(customer.Address.ToEntity());
context.InvoicesEntity.InsertAllOnSubmit(customer.Invoices.ToEntity());
}
}

Ok. Later on i have a SubmitChanges() method in the context where i actually persist the data to the database.

Now, i don’t know much, almost anything, about NHibernate. But looking at some examples, i am suspecting that NHibernate takes care of all that breakdown for you (because of the mapping?) so you only have to pass Customer and it will do the rest. Is that Correct?

I am willing to learn NHibernate if I really see a HUGE benefit from it.

Thank you for checking out my question.

EDIT: Have you heard of Codesmithtools.com? They have a framework generator for LinqToSql, EF, NHibernate. Has anyone tried their NHibernate? I have used PLINQO for LinqToSql but they add so much crap to the classes that i believe are unnecessary. Pretty much the classes are suit to be used, for bad programmers, as business classes, DTO, ViewModels, etc. All In One :). Terrible. BUT, they are really good at generating all that. i have to give them KUDOS for that.

Answer 1

Your question is open-ended. It is obvious that you now how Linq-2-SQL works. As the first comment already said: yes NHibernate can provide cascading saves. But this is only the beginning… Please, first of all, check this question and answers (there are more than one interesting):

NHibernate vs LINQ to SQL

I am using NHibernate on my private projects as the first choice. If possible I prefer it on any project. But, I would like to append one more NOTE, from my experinece:

The biggest benefit is, that once you will learn and work with NHibernate, it won’t be so much difficult to work with other ORM tool. On some projects you will (I did) meet Entity Framework on some LLBL Generator…, and (while we can blame that something in comparsion with NHibernate is missing;) we can quickly:

• understand the domain, because ORM forces the Entity/Domain driven implementation
• use standard patterns

Wish it helps and good luck with NHibernate. Learning curve is maybe slower then expected, but benefits await.