Question

I would like to know if is there any interface like IValidatableObject but for test the inputs for ModelState, something like that:

public class EditUserViewModel: IAnyInterface
{
     public string Name{get;set;}
     public string Age{get;set;}

     public IEnumerable<ModelStateError> Validate()
     {
          if(//something)
               yield new ModelStateError("error");
     }
}

ps: I don’t want to use data annotation!

Answer 1

Yes you can do this, but you will need to create a wrapper for your ModelState to check if every property is valid and convert to to send to the View.

You could use a Library called Fluent Validation. It is free, easy to integrate with asp.net mvc and a extensiable library to validate your ViewModel. Take a look:

Fluent Validation Page
http://fluentvalidation.codeplex.com/

Fluent Validation Source (if you need)
https://github.com/JeremySkinner/FluentValidation

ASP.NET MVC Integration:
http://fluentvalidation.codeplex.com/wikipage?title=mvc&referringTitle=Documentation

Doing this, when you called on your post actions ModelState.IsValid it will validate with the fluent validation classes you had setted for the ViewModel.

You also can integrate with a Inversion of Control like Unity, Ninject, StructureMap, etc… to check some informations on the respository before persist it.