ASP.NET MVC Best Practices

The ASP.NET MVC is becoming more and more popular each day.  As the application grows in size so does the maintenance nightmare.  Following are some of the better practices, that if followed, may help maintain our application and also provides a means of scalability as the demand increases.  Feel free to add/update practices/tips as required.

 Do note that this checklist are just for quick reference and are not detailed materials and can be used as a quick reference.  

1. Isolate Controllers
   Isolate the controllers from dependencies on HttpContext, data access classes, configuration, logging etc.  Isolation could be achieved by creating wrapper classes and using an IOC container for passing in these dependencies
   
   
2. IoC Container
   Use an IoC container to manage all external dependencies  The following are some of the wellknown containers/framework.
1. Ninject
2. Autofac
3. StructureMap
4. Unity Block
5. Castle Windsor
   
   
3. No "magic strings"
   Never use magic strings in your code. This means hard-coding view names, link text etc. into your views. Frameworks such as T4MVC can help with this.  More to come on this.
   
   
4. Create a ViewModel for each view
   Create a specialized ViewModel for each view.  The role of ViewModel should only be databinding.  It should not contain any presentation logic.
   
   
5. HtmlHelper
   For generating view html use HtmlHelper.  If  the current HtmlHelper is not sufficient extend it using extension methods.  This will keep the design in check.
   
   
6. Action Methods
   Decorate your action methods with appropriate verbs like Get or Post as applicable.
   
   
7. Caching
   Decorate your most used action methods with OutputCache attribute.
   
   
8. Controller and Domain logic
   Try to keep away domain logic from controller.  Controller should only be responsible for
1. Input validation and sanitization.
2. Get view related data from the model.
3. Return the appropriate view or redirect to another appropriate action method.
   
   
9. Use PRG pattern for data modification
   PRG stands for Post-Redirect-Get to avoid the classic browser warning when refreshing a page after post.  Whenever you make a POST request, once the request complets do a redirect so that a GET request is fired.  In this way when the user refresh the page, the last GET request will be executed rather than the POST thereby avoiding unnecessary usability issue. It can also prevent the initial request being executed twice, thus avoiding possible duplication issues.
   
   
10. Routing
    Design your routes carefully.  The classic route debugger comes to rescue http://haacked.com/archive/2008/03/13/url-routing-debugger.aspx
    
    
11. There should be no domain logic in the views. Views must be, only, responsible for showing the data.
    
    
12. Views should not contain presentation logic
    Views should not contain any presentation logic.  For e.g. If a "Delete" button is to be displayed only for "Admin" role this should be abstracted away in an Html Helper.  This is just an example and there will be many scenarios which will require this abstraction for easy maintenance of views. 
    
    
13. Use POST for "Delete" links instead of GET
    Using Delete links (GET) is more vulnerable than using POST.  Here is a detailed post on this along with a couple of alternatives.
    http://stephenwalther.com/blog/archive/2009/01/21/asp.net-mvc-tip-46-ndash-donrsquot-use-delete-links-because.aspx