Where to put DTOs, Result Objects etc?

Question

Hello,

I have a fairly clean ASP.NET MVC project structure. However, I'm struggling on how to organize the mass of classes which are DTOs (data transfer objects), e.g. just to encapsulate post data from forms (viewmodels) but don't represent full domain objects or anything near that yet; and then the many "result" objects I have which communicate complex result information from my service layer back to the controller. Where do you stuff these/how do you organize them? I have one folder with well over 60 classes now and it's getting cluttered. Appreciate suggestions!

Answer 1

Domain objects should live in a separate Domain Model library. Anything that supports the Domain Model in an framework-neutral way (e.g. no references to ASP.NET MVC, WCF, WPF etc.) belongs in the Domain Model.

Classes that perform translation between the Domain Model and the specific interface framework (ASP.NET MVC in your case) belongs in that particular project (your ASP.NET MVC project).

You can have your mappers etc. in a separate Mappers folder, but personally, I think it is much more valuable to structure code along features instead of infrastructure.

Answer 2

I use <CompanyName>.<ProjectName>.Core to store all project specific classes which are not strictly pertaining to the particular project interface that I am writing. So DTOs, DAOs, other project-specific classes are all in there.

I also use <CompanyName>.<DotNetLibraryNamespace> to store general purpose classes that could be reused across projects, and are not specific to this project domain. For example, string manipulation classes could go in the <CompanyName>.Text namespace. I always mirror the .net namespace structure names so that anyone that uses the .net class library has an easy time finding my stuff.