To get a list of errors in the model state

Controller.cs

[HttpPost]
public ActionResult Edit(ViewModel viewModel)
{
	if (ModelState.IsValid)
	{
		repository.SaveModel(viewModel);
		TempData["message"] = "Changes have been saved";
		return RedirectToAction("Index");
	}
	else
	{
                // Referenced from http://stackoverflow.com/questions/5510814/c-sharp-net-mvc3-modelstate-isvalid - Darin Dimitrov
		ViewBag.Errors = ModelState
			.Where(x => x.Value.Errors.Count > 0)
			.Select(x => new { x.Key, x.Value.Errors })
			.ToArray();
			
		return View(viewModel);
	}
}

View.cshtml

@if (ViewBag.Errors != null)
{
    foreach (var e in ViewBag.Errors)
    {
        <p>@e</p>
    }
}