DDD Questions & Design Approach

bhaidar · February 5th, 2013, 01:44 PM

Hi,

It's the first serious ASP.NET book I ever read. Recommended for each and every ASP.NET developer.

I am kind of new to the idea of DDD. How would I go about learning how to organize my model objects? Is there a way to think when creating such objects?

Thank you

elbandit · February 5th, 2013, 01:54 PM

Create objects based around behaviour rather than nouns and verbs. For example don't create a customer because there is one in real life, instead look for behaviour and model that. In an e-commerce site you have a customer and she can subscribe to a newsletter. Instead of adding all of the behaviour for newsletter subscriptions onto a customer object model a NewsletterSubscriber object. Then perhaps Customer is just the personal details of a person placing an order.

Does that make sense?

bhaidar · February 5th, 2013, 02:00 PM

I end up having a NewsletterSubscriber class having a property of type Customer to capture the Customer's Email for example?

The DDD book explains such concepts?

Thanks

elbandit · February 5th, 2013, 02:19 PM

Maybe you end up with three objects, all built for a single purpose...

Code:

public class NewsletterSubscriber
{
   private int customer_id;
   private bool send_emails_on_offers;
   private bool share_my_info_with_other_companies;
  
}

Code:

public class ContactDetails
{
   private int customer_id;
   private string email;
   private string phone_number
  
}

Code:

public class PersonalDetails
{
   private int customer_id;
   private string first_name;
   private string family_name;
  
}

The objects all have a single reason to change and are focused on a single behaviour. All linked by a corrleation id, the 'customer_id' property. You see there is no 'customer', there is no spoon. :0)