Should View Models in ASP.Net MVC be all strings?

Question

I've got to the point (unintentionally) that I feel in some parts I'm doing too much within the view (.aspx) itself, too much formatting, concatenation, in one place a little regex replace.

I was starting to work on a new part and trying to improve my approach.. Then it hit me why don't I just make all my View Models (in /Models/ in .Web project) strings or a list of string at a push. Note: I'm not referring to my model/domain, but rather to specifically my ViewModel.

public class FinanceQuoteView
{
    public string Provider; 
    public string Broker; // rather than Broker == null ? "N/A" : Broker.ToUpperCase();
    public string Monthly; // rather than Monthly.ToString("C")
    public string PaymentTerm; // rather than "1+" + PaymentTerm.ToString();
    public string FreeInsurance; // rather than insuranceIncluded ? "Yes" : "No";
    public string[] Restrictions;
}

For Form submission (adding editing) I use a seperate view model to feed the controller action (form model if you will in /Models/Form). So FinanceQuoteForm does contain doubles etc... built via a binder.

What everyone think about this approach? Is doing the .ToString("C") in the mapping from domain to view model too much?

Answer 1

Your model should produce the correct data, then it is up to the view to produce the data in the format that it requires. If you built another view on top of the model, you might want to do different manipulations of the data, so i suggest NOT returning them as strings from the model.

Answer 2

I tend to lean pretty heavily towards strings myself for the View Models that I design. After all, most of the data displayed in the View takes the form of strings. Any time I am about to perform data manipulation in the View (.aspx/.ascx), I seriously consider pushing that logic down to my View Model so that I can unit test it. After all, Testability is the major benefit you get from MVC, so why not use it?

In WPF (just to take a short detour) many of the controls natively understand other types of data (such as numbers, booleans and so forth), but on a platform so inherently bound up on strings as HTML, it makes a lot of sense for me to treat most of the output as text.

All data has to round-trip between server and browser encoded as strings anyway, so often, you would just be explicit about it.

I definitely don't think it's too much - I only think you can do it too little :)

Answer 3

Your situation seams to be very special and limited in a way: Your ViewModel is either for editing or Displaying. Most Views do both: they have a lot of display stuff ans some editing stuff. Lets say this Page:

Display question, answers and notes. Edit: Answer.

I would not want to distinguish the 2. It would end in duplication of a lot of display fields.

I would rather have one view with possibly 2 properties: one for display and one for the form value.