Object reference not set to an instance of an object

Question

With this code I have error: Object reference not set to an instance of an object, why

<% using (Html.BeginForm("XMLDevicesAddFirmware","ImportXML",FormMethod.Post)) {%>

<table class="data-table">
    <tr>

        <th>
            Article Number
        </th>
        <th>
            Firmware
        </th>

        <th>
            Name
        </th>
        <th>
            Order Id
        </th>

        <th>
            Software Version
        </th>
    </tr>

<% int rb = 1;%>

<% foreach (var item in Model) { %>

    <tr>

        <td>
            <%= Html.Encode(item.ArticleNumber) %>
        </td>

        <td>
            <input id="Firmware" name="<%= Html.Encode(rb)%>" type="text" />
        </td>

        <td>
            <%= Html.Encode(item.Name) %>
        </td>
        <td>
            <%= Html.Encode(item.OrderId) %>
        </td>

        <td>
            <input id="SoftwareVersion" name="<%= Html.Encode(rb)%>" type="text" />
        </td>
    </tr>
   <% rb = rb + 1;%>
   <% } %>

</table>

        <p>
            <input type="submit" value="Finish" />
        </p>

 <% } %>



    public ActionResult XMLDevicesAddFirmware()
    {

        var dev = from i in XMLEntities.unassigneditems
                  where i.DevOrAcc == true
                  select i;

        return View(dev);
    }



    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult XMLDevicesAddFirmware(FormCollection col)
    {
        //....
        return View();
    }

Stack Trace:

 [NullReferenceException: Object reference not set to an instance of an object.]
 ASP.views_importxml_xmldevicesaddfirmware_aspx.__RenderContent2(HtmlTextWriter __w,     Control parameterContainer) in c:\Documents and Settings\Ognjen\My Documents\Visual Studio 2008\Projects\MvcKVteam - radna verzija_18_07\MvcKVteam - radna verzija\MvcKVteam\Views\ImportXML\XMLDevicesAddFirmware.aspx:36
 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256
 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
 System.Web.UI.Control.Render(HtmlTextWriter writer) +10
 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
 ASP.views_shared_site_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\Documents and Settings\Ognjen\My Documents\Visual Studio 2008\Projects\MvcKVteam - radna verzija_18_07\MvcKVteam - radna verzija\MvcKVteam\Views\Shared\Site.Master:104
 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256
 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
 System.Web.UI.Control.Render(HtmlTextWriter writer) +10
 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134
 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
 System.Web.UI.Page.Render(HtmlTextWriter writer) +29
 System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) +59
 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1266

Answer 1

Is the method public ActionResult XMLDevicesAddFirmware(string Firmware, string SoftwareVersion) being hit. I can't see that your form is posting back to this method, I mean, there is no string Firmware, string SoftwareVersion in the route.

try this

[AcceptVerbs(HttpVerbs.Post)]
    public ActionResult XMLDevicesAddFirmware(FormCollection coll)
    {
        //....
        return View();
    }

edit: or on the Html.BeginForm add new { Firmware = Model.Firmware, SoftwareVersion = Model.SoftwareVersion}

Answer 2

Don't forget to pass the model to the view:

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult XMLDevicesAddFirmware(string Firmware, string SoftwareVersion)
{
    var model = new SomeModel();
    return View(model);
}

Answer 3

If the model is not valid and you are unable to do execute some of your code in the

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult XMLDevicesAddFirmware(FormCollection col)
{
    //....
    return View();
}

you need to return same model to the View()

return View(dev);

like u did with the get action,

otherwise the view cannot display because model is null.

when u do return View(dev); view will render fine, and if u did ModelState.AddModelError(/**/); the view will show validation errors