Confusion over MVC and entity model

问题:

My confusion stems from the fact I am using 2 different walkthroughs on building mvc applications, namely: Steven Sanderson's pro asp.net mvc and the online mvc music store. The former creates a domain model, placing the entity model in there along with repositories, while the music store demo places the entity model in the mvc model folder. Which of these is the best approach. Should the entity model and associated repositories exist in a separate domain layer, or in the MVCs model folder.

回答1:

Separation of concerns

Model folder in Asp.net MVC project template is indeed very confusing. Most developers not knowing enough about MVC pattern think that application/domain model = data model. Most of the time, that's not the case.

Take for instance a user entity that may be in several different forms:

• NewUser is an application model entity that has most properties of a user, plus two password properties that can be declaratively validated
• User data model entity has all usual user properties and one password property
• User application model entity has all the usual properties and none for password

So you can see by this simple example there are multiple models that differ between each other. And when you have a multi-assemblied application, putting application model in a separate assembly is very wise, since all assemblies will most probably communicate using these objects only. No data model entities should be transferred outside data assembly/tier to make use of SoC...

So in the end it's ok to put data model in the Model folder when building a small scale simple application, but in all other cases it's probably better to use a separate application model assembly that's shared between all assemblies. And have a separate data model that's only used in data tier assembly.

Read this answer that may help you see things a bit clearer.
And this one as well.

I would recommend against using the Model folder and use a separate assembly instead. You'll have better separation and improved scalability.

回答2:

Strategically it makes sense to place the EF Model in the same folder as the repositories, because it just is a part of the Data-Access-Layer inside an application.

Logically it would be better to place the EF model in the Model directory as it creates all classes needed to reflect the database in an application. (And if you open the Class View it looks way better to have all those classes residing in a folder called Model instead of Repositories)

At our company we've had the same problem and decided to go with saving the EF model in the Model folder.

After all it's up to you what you do. The most important thing to do here would be to document all kinds decisions that happen during development (when, why and based on what).

Documenting everything could prevent later WTF's