How does asp.net MVC remember my incorrect values on postback?

Question

This is working, but how???

I have a controller action for a post:

[AcceptVerbs(HttpVerbs.Post )]
public ActionResult Edit(Person person)
{
   bool i         


        

Answer 1

I had some code in the 'postback' that would remove invalid promo-codes and capitalize the response. Even if you update the model with the new value it won't be displayed because the ModelState value takes precedence (as others have already answered).

  <%= Html.TextBox("PromoCode", Model.PromoCodes) %>

But if you have a case where this was happening and you don't want the old value persisted you need to do this:

ModelState.Remove("PromoCode"); 

or explicitly set the new value into modelstate (probably the better approach) :

ModelState.SetModelValue("PromoCode", 
      new ValueProviderResult(newValue, newValue, CultureInfo.CurrentCulture));