Does Html.TextBox uses Request.Params instead of Model?

Question

I have a simple test application:

Model:

public class Counter
{
    public int Count { get; set; }

    public Counter()
    {
        Count = 4;
    }
}

Controller:

public class TestController : Controller
{
    public ActionResult Increment(Counter counter)
    {
        counter.Count++;
        return View(counter);
    }
}

View:

<form action="/test/increment" method="post">
    <input type="text" name="Count" value="<%= Model.Count %>" />
    <input type="submit" value="Submit" /> 
</form>

Clicking Submit I get such values:

5, 6, 7, 8, ...

With Html.TextBox I expected the same behaviour

<form action="/test/increment" method="post">
    <%= Html.TextBox("Count") %>
    <input type="submit" value="Submit" /> 
</form>

but actually got

5, 5, 5, 5.

It seems Html.TextBox uses Request.Params instead of Model?

Alexander Prokofyev · Accepted Answer · 2009-06-05 07:12:23Z

8

Html.TextBox() uses internally ViewData.Eval() method which first attempts to retrieve a value from the dictionary ViewData.ModelState and next to retrieve the value from a property of the ViewData.Model. This is done to allow restoring entered values after invalid form submit.

Removing Count value from ViewData.ModelState dictionary helps:

public ActionResult Increment(Counter counter)
{
    counter.Count++;
    ViewData.ModelState.Remove("Count");
    return View(counter);
}

Another solution is to make two different controller methods for GET and POST operations:

public ActionResult Increment(int? count)
{
    Counter counter = new Counter();

    if (count != null)
        counter.Count = count.Value;

    return View("Increment", counter);
}

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Increment(Counter counter)
{
    counter.Count++;

    return RedirectToAction("Increment", counter);
}

Counter object could also be passed via TempData dictionary.

You may also be interested in the article Repopulate Form Fields with ViewData.Eval() by Stephen Walther.

edited Jun 5, 2009 at 7:12

answered Jun 5, 2009 at 6:36

Alexander Prokofyev

34.6k33 gold badges101 silver badges118 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Mehrdad Afshari Over a year ago

Then why specifying Model.Count explicitly doesn't work? <%= Html.TextBox("Count", Model.Count) %>

Alexander Prokofyev Over a year ago

Because at first Html.TextBox() takes value from ModelState dictionary.

James H · Accepted Answer · 2009-06-04 23:44:36Z

1

That's not the issue here. Specifying

<%= Html.TextBox("Count") %>

is equivalent to specifying

<%= Html.TextBox("Count", null) %>

which will pull the matching value (named "Count") from the ModelStateDictionary.

But even so, explicitly passing in

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

results in the same behavior described by alex2k8.

answered Jun 4, 2009 at 23:44

James H

2,3993 gold badges22 silver badges20 bronze badges

Comments

Daniel A. White · Accepted Answer · 2009-06-04 23:44:55Z

0

Html.TextBox has more parameters than one..first parameter is the name or id of input element, and the second one is the value...

so write your textbox helper like this:

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

cheers

edited Jun 4, 2009 at 23:44

Daniel A. White

192k49 gold badges389 silver badges473 bronze badges

answered Jun 4, 2009 at 23:27

Marko

1,9421 gold badge21 silver badges37 bronze badges

Collectives™ on Stack Overflow

Does Html.TextBox uses Request.Params instead of Model?

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related