ViewData and ViewModel in MVC ASP.NET

Question

I'm new to .Net development, and now are following NerdDinner tutorial. Just wondering if any of you would be able to tell me

What is the differences between ViewData and ViewModel

(all I know is they are used to pass some form of data from controller to view) and perhaps tell me on what situation should I use ViewData instead of ViewModel and vice versa

Thanks in advance!

Sally

Answer 1

ViewData:

In short, use ViewData as support data, such as a datasource to a SelectList.

ViewModel:

ASP.NET MVC ViewModel Pattern

When a Controller class decides to render an HTML response back to a client, it is responsible for explicitly passing to the view template all of the data needed to render the response. View templates should never perform any data retrieval or application logic – and should instead limit themselves to only have rendering code that is driven off of the model/data passed to it by the controller.

[...]

When using [the "ViewModel"] pattern we create strongly-typed classes that are optimized for our specific view scenarios, and which expose properties for the dynamic values/content needed by our view templates. Our controller classes can then populate and pass these view-optimized classes to our view template to use. This enables type-safety, compile-time checking, and editor intellisense within view templates.