Question

In an mvc 3 .Net FW 4.0 project I have a data that relates in a parent child relationship, I’ve built up my model to contain a list of “children” with each parent record, and displaying it as in the following example:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/ViewMasterPage.Master" Inherits="System.Web.Mvc.ViewPage<MvcTest.Models.ModelList>" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
    ShowPropReturn
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

<h2>ShowPropReturn</h2>

<script src="<%: Url.Content("~/Scripts/jquery.validate.min.js") %>" type="text/javascript"></script>
<script src="<%: Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js") %>" type="text/javascript"></script>

<% using (Html.BeginForm()) { %>
    <%: Html.ValidationSummary(true) %>
    <fieldset>
        <legend>ModelList</legend>

        <div class="editor-label">
            <%: Html.LabelFor(model => model.MyProperty1) %>
        </div>
        <div class="editor-field">
            <%: Html.EditorFor(model => model.MyProperty1) %>
            <%: Html.ValidationMessageFor(model => model.MyProperty1) %>
        </div>

        <div class="editor-label">
            <%: Html.LabelFor(model => model.MyProperty2) %>
        </div>
        <div class="editor-field">
            <%: Html.EditorFor(model => model.MyProperty2) %>
            <%: Html.ValidationMessageFor(model => model.MyProperty2) %>
        </div>

        <table>
        <% foreach (var item in Model.MyProperty3)
           { %>
                <tr>
                    <td>
                        <%: Html.TextBoxFor(i => item.string1) %>
                    </td>
                    <td>
                        <%: Html.TextBoxFor(i => item.string2) %>
                    </td>
                </tr>

        <% } %>
        </table>
        <p>
            <input type="submit" value="Save" />
        </p>
    </fieldset>
<% } %>

<div>
    <%: Html.ActionLink("Back to List", "Index") %>
</div>

</asp:Content>

I figured out that if a displayfor is used to only display a field value, it does not get posted back which makes sense. But I’m getting a null for the child list object in the model on httppost and I need to have these items edited on the same view, it is also null in the formcollection object, can anyone help me on this please?

Answer 1

Instead of the foreach loop try using an editor template:

<table>
    <%= Html.EditorFor(x => x.MyProperty3)
</table>

and inside the corresponding editor template (~/Views/Shared/EditorTemplates/SomeModelType.ascx):

<%@ Control Language="C#" 
    Inherits="System.Web.Mvc.ViewUserControl<AppName.SomeModelType>" 
%>
<tr>
    <td>
        <%= Html.TextBoxFor(x => x.string1) %>
    </td>
    <td>
        <%= Html.TextBoxFor(x => x.string2) %>
    </td>
</tr>

Now this will generate proper input field names so that when you submit the form values will be correctly bound.

Remark: In this case I assume that MyProperty3 on your main view model is defined like this (a collection of SomeModelType):

public IEnumerable<SomeModelType> MyProperty3 { get; set; }