How do I map an inheritance hierarchy with Automapper?

Question

I have the following example classes being used in an MVC/MVVM type app:

class A
{
   public string Property1 { get; set; }
}

class B : A
{
   public string Property2 { get; set; }
}

class ViewModel
{
   public string Property1 { get; set; }
   public string Property2 { get; set; }
}

A is my base class and B is the derived class. ViewModel is meant to encompass both A & B.

I want to use AutoMapper to map from both A & B to ViewModel. What is the best way to do this?

Assuming I have complex properties on A that require a .ForMember call, do I then have to repeat the same mappings for those complex properties when creating the map from B to ViewModel or is there a way to inherit/reuse the map from A to ViewModel?

Answer 1

If you map A to ViewModel, you will need to Ignore() members that don't exist on A, and repeat any configuration that needs to be shared.

Inheritance is just a tough nut, where behavior starts to become complex and less conventional. You can, however, create an extension method on the configuration API to encapsulate all of the duplicate configuration calls.