CODEWITHSUNDEEP
c#asp.net-mvc-4razor
ZxCvBnM
ZxCvBnM

Reputation: 377

Different values from model

I have this two lines in a Razor template:

@Html.Hidden("step", Model.Step)
<p>@Html.Label(Model.Step.ToString())</p>

And they produce two different values:

<input data-val="true"
       data-val-number="The field Step must be a number."
       data-val-required="The Step field is required."
       id="step"
       name="step"
       type="hidden"
       value="0">
    <p>
        <label for="">1
        </label>
    </p>

How is this possible?

Property Step is of a type Int32 and is incremented every POST action.

EDIT:

@model ***.WebUI.Models.OrderViewModel
@{
  ViewBag.Title = "New order";
}
<h2>
  New order</h2>
@using (Html.BeginForm())
{
  @Html.Hidden("step", Model.Step)
  <p>@Html.Label(Model.Step.ToString())</p>
  <div>
    //other inputs
  </div>
}

Upvotes: 3

Views: 279

Answers (1)

user3559349
user3559349

Reputation:

You have not shown you POST method, but based on "Property Step is of a type Int32 and is incremented every POST action." I assume it looks something like

public ActionResult Edit(OrderViewModel model)
{
  model.Step = model.Step + 1;
  return View(model);
}

When you post a model, the models values are added to ModelState (along with any ModelState errors) so in the first post, the ModelState value of Step will be 0. Html helpers use ModelState values for binding (if one exists) so when you return the view @Html.Hidden("step", Model.Step) will bind to the value of 0 (not the models value of 1). The reason for this behavior is explained in this answer.

The correct approach is to follow the PRG pattern (redirect to the GET method, passing a parameter indicating the Step value and initialize a new OrderViewModel), however you can make this work by clearing ModelState so that the Html Helper will use the model value.

public ActionResult Edit(OrderViewModel model)
{
  ModelState.Clear(); // clear all model state
  model.Step = model.Step + 1;
  return View();
}

However, use this with caution. ModelState.Clear() removes all errors as well.

Upvotes: 2

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