C# ASP.NET MVC error sharing model between parent and child view using Html.RenderPartial

Question

While invoking @Html.RenderPartial("_ChildPartialView"), I am getting the following error :

System.Collections.Generic.ICollection' has no applicable method named 'ElementAt' but appears to have an extension method by that name. Extension methods cannot be dynamically dispatched. Consider casting the dynamic arguments or calling the extension method without the extension method syntax

_Testpaper.cshtml parent view:

    for (i = 0; i < Model.Questions.Count;i++)
    {
        ViewBag.QuestionNumber = i;
        Html.RenderPartial("_QuestionDetail"); //Line causing error
    }

_QuestionDetail.cshtml child view:

@model StandardVBA.ViewModels.AssessmentModel
<tr style="padding:4px 0px; background-color:lightskyblue; font-weight:bold;font-family:Cambria;">
    <td style="text-align:left;">
        Q @(ViewBag.QuestionNumber + 1) &nbsp @Model.Questions.ElementAt(ViewBag.QuestionNumber).Question
    </td>
    <td style="text-align:center">
        ( @Model.Questions.ElementAt(ViewBag.QuestionNumber).Marks )
    </td>
</tr>
<tr>
    <td class="questions">
        <ol type="A">
            @for (int j = 0; j < Model.Questions.ElementAt(ViewBag.QuestionNumber).QuestionDetails.Count; j++)
            {
                <li>
                    <div style="display: inline-block; vertical-align: top;">
                        @Html.CheckBoxFor(m => m.Questions.ElementAt(ViewBag.QuestionNumber).QuestionDetails.ElementAt(j).IsSelected)
                    </div>

                    @Html.DisplayFor(m => m.Questions.ElementAt(ViewBag.QuestionNumber).QuestionDetails.ElementAt(j).Choice)
                    @Html.HiddenFor(m => m.Questions.ElementAt(ViewBag.QuestionNumber).QuestionDetails.ElementAt(j).IsCorrect)
                </li>
            }
        </ol>

    </td>
</tr>

I also want to know: why it is mandatory to specify the @Model in the child-view when the child-view shares the same model in a RenderPartial call?

score 1 · Accepted Answer · answered Feb 03 '19 at 07:26

You need to pass the model to the child partial view like this:

for (i = 0; i < Model.Questions.Count;i++)
{
    ViewBag.QuestionNumber = i;
    Html.RenderPartial("_QuestionDetail", Model.Questions[i]); //Line causing error
}

Ensure that the type of Model.Questions[i] matches with the model declaration in the child partial view "@model StandardVBA.ViewModels.AssessmentModel" otherwise you will get the runtime error.

Hope it helps.

score 0 · Answer 2 · answered Feb 03 '19 at 07:14

First you are not passing model to you child view, and using the @model in the child view so fix it by passing the model to your child view like this

    for (i = 0; i < Model.Questions.Count;i++)
    {
        ViewBag.QuestionNumber = i;
        Html.RenderPartial("_QuestionDetail", Model); //Line causing error
    }

secondly you are using @Html.CheckBoxFor(m => m.Questions.......) in your detail view which is your child view, so you need to declare @model...... to use model in your views.

hope this will work!

C# ASP.NET MVC error sharing model between parent and child view using Html.RenderPartial

2 Answers2