Hiddenfor not getting correct value from view model

Question

I have a multi-step file import process. I have a hidden form input in my view that I am trying to populate with the \"CurrentStep\" from the view model.

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Answer 1

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.

Answer 2

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 };
    }
}

Answer 3

Let me add this simple reminder as well in addition to all of these correct answers.
Watch your syntax!
In Razor, both of these statements compile with no errors.

 Html.HiddenFor(i => i.Id); //Compiles, but doesn't bind 
@Html.HiddenFor(i => i.Id); //Compiles and bind 

I was struggling to bind my Id and post it back to an Action.
Though it was always empty.
I was missing the @ symbol!

Answer 4

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