MVC Validation using Data Annotations - Model classes or View Model classes?

Question

Is it best practice to put data validation annotations in the Model or View Model? What are the advantages/disadvantages of one approach over the other?

Curious to see w

Answer 1

Put your Annotations in your Viewmodel.

It is possible to have multiple ViewModels for each DataModel, eg DisplayModel, EditModel, ListModel .. all which may require different annotations.

It is generally considered best practice not to expose your DataModel directly to a view, espcicially in "POST"/Edit scenarios.

I suggest reading Brad Wilson's excellent overview at: http://bradwilson.typepad.com/blog/2009/10/aspnet-mvc-2-templates-part-1-introduction.html

These articles primarily cover the use of Dislpay and Edit templates within MVC2, but clearly illustrate the advantages of using the ViewModel pattern