Displaying modelstate error

Question

I am having the following code, However the errors causght not being displayed. What is wrong ?

  public ActionResult DeleteRateGroup(int id)
    {
        try
        {
           RateGroup.Load(id).Delete();

            RateGroupListModel list = new RateGroupListModel();
            return GetIndexView(list);
        }
        catch (Exception e)
        {
            RateGroupListModel model = new RateGroupListModel(); 

            if (e.InnerException != null)
            {
                if (e.InnerException.Message.Contains("REFERENCE constraint"))
                    ModelState.AddModelError("Error", "The user has related information and cannot be deleted.");
            }
            else
            {
                ModelState.AddModelError("Error", e.Message);
            }
            return RedirectToAction("RateGroup", model);
        }
    }

---

    @model MvcUI.Models.RateGroupListModel

@{
    View.Title = "RateGroup";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Rate Group</h2>

@Html.ValidationSummary()

@using (Html.BeginForm())

---

    private ActionResult GetIndexView(RateGroupListModel model)
    {
       return View("RateGroup", model);
    }

    public ActionResult RateGroup(RateGroupListModel model)
    {
       return GetIndexView(model);
    }

Answer 1

It looks like you're setting the ModelState error, then redirecting to another action. I'm pretty sure the ModelState gets lost when you do that.

Typically, you'd just render the RateGroup view directly from the DeleteRateGroup action, without the redirect, passing in your model if needed, like this:

return View("RateGroup", model);

If you want the ModelState to come along to the second action with you, take a look at MvcContrib's ModelStateToTempDataAttribute. Here's the attribute's description, from the MvcContrib source code's comments:

When a RedirectToRouteResult is returned from an action, anything in the ViewData.ModelState dictionary will be copied into TempData. When a ViewResultBase is returned from an action, any ModelState entries that were previously copied to TempData will be copied back to the ModelState dictionary.