Mapping Domain Models to View Models

3
votes

I'm starting from a point very similar to: Domain Entities, DTO, and View Models.

The advised use of DTOs to map between the domain model and the MVC's ViewModel seems consistent expectations. I seek details of how to bridge the domain model (Entity Framework-based project) to the WebAPI mvc project.

I'm starting with a project of simple POCOs (generated by EF PowerTools to reverse engineer my existent db) that I want to connect to an MVC4 WebAPI project.

I expect I'll be adding business logic to the baseline POCO project as my solution evolves and perhaps this is the crux of this issue. The business logic that transforms the POCOs into something that can be mapped to the MVC project.

Exactly how do I wire these projects together so i can start creating controllers in the MVC project that knows about the entities of the EF project? Automapper? Can we point to posts/docs where this specific feature of Automapper is employed?

1
asp.net-mvcentity-frameworkautomapper

1 Answers

1
votes

You don't want controllers that knows about the EF entities - that's the whole point of this. :)

You yourself say that the DTOs should be used to map your domain to your view model, and then you ask "how can I bridge my domain model with the mvc controllers?". You've already answered this - with DTOs!

The DTO serves as a transport layer between complex business objects and models used to display a certain view. Both of these have special requirements that don't strictly relate to "just data" - hence using DTOs will give you a greater decoupling and separation of concerns.

If you don't decouple domain from view model, you will be forced to directly reference your EF objects in your view model code, which exposes unnecessary data and functions "up the chain".

Now, if you use WebAPI as a way to ship data then I think you could usually get away with sending the DTOs, since WebAPI data usually wouldn't be implementing view model logic. But YMMV of course, depending on how you plan to use your controllers.

For AutoMapper I'd say it's best to start with their own docs (they even use DTO examples in them): http://github.com/AutoMapper/AutoMapper/wiki/Getting-started