Question

I have a ASP.NET MVC 2.0 application using Entity Framework. All my views use view models, most of them complex. Meaning…the object to be edited is a property of the view model, and not the view model itself.

I am using partial classes with data annotations, and checking ModelState.IsValid inside the POST actions in the controller.

I have a “NEW” form and an “EDIT” form for a simple object with 3 fields!

The ModelState.IsValid check works on the NEW form, and shows the correct “required field” errors, if I try to submit a blank form.

But if I load an EDIT form, and clear the values from some textboxes that are required, and submit the form, I do NOT get validation errors, I just get an exception:

Error executing child request for handler ‘System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerWrapper’.

So my question is, does ModelState.IsValid not work with an EDIT form, since perhaps it’s looking at the values from the view model object that were loaded, instead of the FormCollection?

    // this one does not validate

        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Edit(int accountStatusKey, AccountStatusEditViewModel model, FormCollection values)
        {
            if (ModelState.IsValid)
            {
                db.UpdateAccountStatus(accountStatusKey, values);
                return RedirectToAction("States");
            }
            else
            {
                return View("Edit", model);
            }
        }


    // this one does validate

        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult New(AccountStatusNewViewModel model, FormCollection values)
        {
            if (ModelState.IsValid)
            {
                db.AddAccountStatus(values);

                return View("States", new AccountStatusStatesViewModel());
            }
            else
            {
                return View("New", model);
            }
        }

    // how I arrive AT the edit form

        [AcceptVerbs(HttpVerbs.Get)]
        public ActionResult Edit(int accountStatusKey)
        {
            return View("Edit", new AccountStatusEditViewModel(accountStatusKey));
        }

    // and finally, the view model code

    public class AccountStatusEditViewModel : ViewModelBase
    {

        public AccountStatus AccountStatus { get; private set; }

        public IEnumerable States { get; private set; }

        public List StatusTypes { get; private set; }

        public AccountStatusEditViewModel(int accountStatusKey)
        {
            AccountStatus = db.GetAccountStatusByKey(accountStatusKey);
            States = db.GetAllStates();

            StatusTypes = new List();
            StatusTypes.Add("Primary Status");
            StatusTypes.Add("Secondary Status");
            StatusTypes.Add("External Status");
        }

        public AccountStatusEditViewModel()
        {
        }

    }

    // this action method does not work at all either - no db updating, no validation
    // the page simply redirects to "States" view, which should only happen if the db
    // was being updated, right?  But nothing is changing in the DB, and the validation
    // never happens.

        [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Edit(AccountStatusEditViewModel model)
        {
            if (ModelState.IsValid)
            {
                if (TryUpdateModel(model, "AccountStatus"))
                {
                    return RedirectToAction("States");
                }
                else
                {
                    return View("Edit", model);
                }
            }
            else
            {
                return View("Edit", model);
            }

        }

Answer 1

Since the 2.0 version of MVC i’m not using the formcollection anymore.

I only use the viewmodel in the action’s parameter when i have a post, like this:

[HttpPost]
public ActionResult Activatecard(ActivateCardViewModel model)
{

When ‘it’ can’t create my model (entered blabla for a datetime field, or when the validations are not met (i use the validation attributes from the System.ComponentModel.DataAnnotations namespace) i get the ModelState.IsValid equals to false.

I created a blank asp.net mvc2 app, and this was the model that the standard template used for the logon action.