我可以在我的 ApplicationLogic 项目（net standard 2.1）中的 MVC（.net core 3.0）项目中使用视图模型吗？

Question

I have an MVC app where all my view models are in. I added a Business Logic layer project, which is a class library project net standard 2.1, where all my interfaces and services are. I am trying to use my viewmodels in the business logic project, but I can not reference them there. I wanted to know can I reference an MVC app in a class library, if not where can I put my view models if I don't want to add DTOs because my app is not a very big project.

Answer 1

There's a lot of confusion here. First, there's nothing magical about a view model or DTO, and the names are merely descriptive of a particular context of usage. At the end of the day, you have a class that represents some collection of data in a particular context: that is all. Second, business logic is not application logic. Application logic is about presentation and user interaction, whereas business logic is about raw data. Those two things should not cross because business rules should not determine presentation and presentation should not determine business rules.

The business layer should not know anything about your view models in your application layer (the MVC app), as that would create a tight coupling (and a circular reference, FWIW). The logic for mapping to/from the view models in the application layer to the entities in the business layer is the domain of the application layer alone.