I am new to Entity Framework (Code first, if it matters). As I have been using it, I have been building my POCO classes, thinking of them as final domain models. With things like Lazy Loading, I like the Idea that I can use these entities directly in my presentation layer, getting to lazy load the stuff that I actually need.
However, I also recently learned about Data Transfer Objects, something I hadn't heard of before. It absolutely makes sense; the behavior of my final Domain Model might have some business rules that don't belong in the DAL. For instance, should the POCO SalesOrder that i give to Entity Framework include it's final methods like AddItem(Product), which throws an exception if Product has a DiscontinuedDate that is before the SalesOrder.OrderDate. That definitely sounds like stuff that belongs in the BLL.
So, I suppose this means that the POCO classes that I give Entity Framework should be more like DTO's?, like SalesOrderDto and EmployeeDto just simple little data holders with just properties and no methods that then get mapped (probably using AutoMapper) to Domain Objects in my BLL, which then get passed to the Presentation Layer?
Am I on the right track here, Or am I missing something. I feel confused because the idea of DTO's make perfect sense, but I have never seen them used in the context of Entity Framework.
Entity Framework is an Object Relatonal Mapper. Entities are therefore mappings to your relational tables.
They are
simple little data holders with just properties and no methods
yes.