asp.net mvc viewdata display in a viewpage

Question

I sent a viewdata to a view page like this.

 public ActionResult SelectRes(int id)
    {
        var ResList = resrepository.GetAll();
        ViewData["ResList"] = new SelectList(ResList, "ResId", "Res_KORNM");

        return View(svcresrelationRepository.GetAll());
    }



@foreach (var item in ViewData["ResList"] as List<ITSDapper.Dapper.Resource>)
        {
            <tr>
                <td style="text-align:center;">
                    @Html.DisplayFor(a=> item.Res_KORNM)
                </td>
            </tr>
        }

And I tried to display the viewdata in a view page but it's not worked. (Object reference not set to an instance of an object)

How display the viewdata in foreach statement?

hutchonoid · Accepted Answer · 2015-05-29 10:07:45Z

1

You would typically use a SelectList for data that is to be selected by a user.

If this is the intention you can just use an Html.DropDownList:

@Html.DropDownList("SelectedId", 
                         (IEnumerable<SelectListItem>)ViewData["ResList"])

If you are simply needing to view the data, I would change your server-side code to use something other than a SelectList.

This could be done as follows:

Controller

 public ActionResult SelectRes(int id)
    {
        var ResList = resrepository.GetAll();

        ViewData["ResList"] = ResList;

        return View(svcresrelationRepository.GetAll());
    }

View

@foreach (var item in ViewData["ResList"] as List<ITSDapper.Dapper.Resource>)
        {
            <tr>
                <td style="text-align:center;">
                    @Html.DisplayFor(a=> item.Res_KORNM)
                </td>
            </tr>
        }

edited May 29, 2015 at 10:07

answered May 29, 2015 at 9:56

hutchonoid

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4 Comments

Ehsan Sajjad Over a year ago

the point is he is converting reference to wrong type, from current code it is not clear he wants a dropdown or not?

hutchonoid Over a year ago

@EhsanSajjad Doesn't make sense to generate a SelectList for data from server-side though surely? Simply making the code compile is not the best answer.

Roy Over a year ago

@ hutchonoid : You're right. I misused the expression from used a dropdownlist. I should wrote like that;

hutchonoid Over a year ago

@Roy At least your sorted now. :)

Ehsan Sajjad · Accepted Answer · 2015-05-29 09:56:35Z

0

You are converting reference to wrong type, you are creating SelectList instance while in View you are convering it to IList<T>, you should convert it to SelectList:

@foreach (var item in ViewData["ResList"] as SelectList)
        {
            <tr>
                <td style="text-align:center;">
                    @Html.DisplayFor(a=> item.Text)  // note this as well
                </td>
            </tr>
        }

answered May 29, 2015 at 9:56

Ehsan Sajjad

62.6k16 gold badges112 silver badges171 bronze badges

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