Best Practices for ASP.NET MVC

Question

Basically, this 'question' is intended to pool information about best practices in the community. The reasons for this are:

• The distinct lack of an community based ASP.NET MVC resource for best practices. Yes, I am aware of wiki.asp.net.
• I'm painfully aware that the ASP.NET wiki on ASP.NET MVC is woefully small and terribly out of date and needs fleshing out more by Microsoft before the community does anything with it.
• I'm very much interested in best practices in general, having had a fair degree of experience with ASP.NET MVC over the last year, but I'm also mindful that I'm no expert, and that I can definitely improve. This post, I believe, can help that, and you.

I gave some serious thought on whether or not I should ask this question, even going to the lengths of creating a question on meta about creating this question. :)

What I am looking for is for best practice information on all aspects of ASP.NET MVC. Controllers, models, extensions, HTML helpers, route builders, TDD.

In the past, I have found resources, such as Kazi Manzur Rashid's best practices (part 1 and 2) post quite useful, along with Maarten Balliauw's weigh-in, but these have dried up somewhat, and I was hoping for a more dynamic and growing repository of information from different people, rather than just the occasional blog entry from learned individuals. Information like this is few and far between, and ASP.NET MVC community resources even less so.

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MVC in general

Model

Feel free to add model links

Views

Controller

Feel free to add controller links

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Guidelines:

• One "best practice" per answer
• Take the time to explain why it should be preferred over the alternatives.
• Read existing answers first - if you see one you agree with, up-vote it; if you disagree, down-vote and leave a comment explaining why.
• Feel free to edit any answer if you can expand on why it is "best"!

P.S. Please don't just put "Anything by Phil Haack, Scott Guthrie, Rob Conery or Scott Hanselman"!

Answer 1

While not a best practices site, the below site is doing great things with asp.net MVC that could probably be considered best practice.

http://www.codeplex.com/MVCContrib

Answer 2

1. IoC/DI for Controller factory (so I can inject IRepository, ISomeService in controllers constructor)
2. never access HttpContext directly, build wrapper, so it can be unit tested
3. Validation framework for model binding validations (xVal or FluentValidation). Built-in validation inside MVC 1 is basic
4. never use "magic strings": for calling controllers/actions from View, for RouteLink, RenderPartial, RenderAction, ...
5. never use ViewData, build DTO ViewModel classes. Use AutoMapper for mapping data from domain entities to ViewModel DTO objects for View

ViewModel DTO objects:
BaseViewModel abstract class, with properties for rendering page meta data, menus and all other stuff that appears on every page. All other ViewModel classes inherits from BaseViewModel.

Answer 3

Keep any and all logic out of your view. Your controller should determine what gets shown - your view should be dumb.

Answer 4

Use T4MVC to eliminate all magic strings and magic anonymous types in your entire project. This will help you in refactoring later in your project, and (apart from having to still ensure your routes are well-defined) all Action calls get their proper parameters. It changes calls like this:

<%= Html.ActionLink("Link text", "Products", "Details", new { id = Model.Id }) %>

Into:

<%= Html.ActionLink("Link text", MVC.Products.Details(Model.Id)) %>

Answer 5

There are 2 free chapters available for the book "MVC in Action".

http://www.manning.com/palermo/

Chapter 12 is best practices.

Answer 6

Keep your controllers as "thin" as possible. Simply have them validate data coming in from the form, and then calling the model (which does all the real work) to get the data to be returned in your next View.

Having complex controllers kind of breaks the MVC concept.