Is this a proper implementation of n-layer architecture?

Question

I have been learning C# for the last year or so and trying to incorporate best practices along the way. Between StackOverflow and other web resources, I thought I was on the ri

Answer 1

What others have said about using an ORM - as your model expands, you are going to have a lot of code repetition without one. But I wanted to comment on your "what about 5,000" question.

Copying a class does not create 5,000 copies of its methods. It only creates a copy of the data structures. There is no lost efficiency to having the business logic in the domain object. If some of the business logic is not applicable, then you could create subclasses that decorate the object for specific purposes, but the purpose of this is to create objects that match your intended use, not efficiency. An anemic design model is not more efficient.

Also, think about how you will use data in your application. I can't think of a single time I've ever used a method like "GetAllOfSomething()", except for maybe a reference list. What is the purpose of retrieving everything in your database? If it's to do some process, data manipulation, report, you should be exposing a method that performs that process. If you need to expose a list for some external use, like populating a grid, then expose an IEnumerable and provide methods for subsetting data. If you start with the idea that you work with complete lists of data in memory you'll have serious performance problems as the data grows.