Hiddenfor not getting correct value from view model

What you are doing wrong is that you are trying to modify the value of a POSTed variable in your controller action. So I suppose you are trying to do this:

[HttpPost]
public ActionResult Foo(SomeModel model)
{
    model.CurrentStep = Steps.SomeNewValue;
    return View(model);
}

and html helpers such as HiddenFor will always first use the POSTed value and after that the value in the model.

So you have a couple of possibilities:

1. Remove the value from the modelstate:

   [HttpPost]
   public ActionResult Foo(SomeModel model)
   {
       ModelState.Remove("CurrentStep");            
       model.CurrentStep = Steps.SomeNewValue;
       return View(model);
   }
   

2. Manually generate the hidden field

   <input type="hidden" name="NextStep" value="<%= Model.CurrentStep %>" />
   

3. Write a custom helper which will use the value of your model and not the one that's being POSTed

My solution was to use Darin's second option, because option 1 (clearing from the model state) means hard coding a string (and the naming convention can be tricky with complex models), and wanted to avoid option 3 because I already have so many custom helpers.

<input type="hidden" name="@Html.NameFor(x => Model.SomeId)" value="@Model.SomeId" />

Just a reminder that you can use Html.NameFor to keep things clean.

Make sure you model property has a "set" operator.

This won't get updated on post-back:

@Html.HiddenFor( m => m.NoSeq)

public Class MyModel
{
    int _NoSeq;
    public NoSeq
    {
        get { return _NoSeq };
    }
}