c# - Model binding with nested child models and PartialViews in ASP.NET MVC

Question

I have the following types and classes:

namespace MVC.Models

public class Page 
{
   public EditableContent Content {get; set; }
}

public class EditableContent
{
    public TemplateSection SidebarLeft {get; set; }
    public TemplateSection SidebarRight {get; set; }
}

I want to edit the Page instance in my Edit.aspx View. Because EditableContent is also attached to other models, I have a PartialView called ContentEditor.ascx that is strongly typed and takes an instance of EditableContent and renders it.

The rendering part all works fine, but when I post - everything inside my ContentEditor is not binded - which means that Page.Content is null.

On the PartialView, I use strongly typed Html Helpers to do this:

<%= Html.HiddenFor(m => m.TemplateId) %>

But because the input elements on the form that are rendered by ContentEditor.ascx does not get the Content prefix to its id attribute - the values are not binded to Page.

I tried using loosely typed helpers to overcome this:

<%= Html.Hidden("Content.TemplateId", Model.TemplateId) %>

And when I'm dealing with a property that is a List<T> of something it gets very ugly. I then have to render collection indexes manually.

Should I put both Page and EditableContent as parameters to the controller action?:

public ActionResult Edit(Page page, EditableContent content) { ... }

What am I missing?

Answer 1

I would suggest you to use the EditorFor helper

Model:

public class EditableContent
{
    public string SidebarLeft { get; set; }
    public string SidebarRight { get; set; }
}

public class Page
{
    public EditableContent Content { get; set; }
}

Views/Home/Index.aspx:

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<ToDD.Models.Page>" %>

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

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<% using (Html.BeginForm()) { %>
    <%-- 
    This is the important part: It will look for 
    Views/Shared/EditorTemplates/EditableContent.ascx
    and render it. You could also specify a prefix
    --%>
    <%= Html.EditorFor(page => page.Content, "Content") %>
    <input type="submit" value="create" />
<% } %>
</asp:Content>

Views/Shared/EditorTemplates/EditableContent.ascx:

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<ToDD.Models.EditableContent>" %>

<%= Html.TextBoxFor(m => m.SidebarLeft) %>
<br/>
<%= Html.TextBoxFor(m => m.SidebarRight) %>

And finally Controller/HomeController:

public class HomeController : Controller
{
    public ActionResult Edit()
    {
        var page = new Page
        {
            Content = new EditableContent
            {
                SidebarLeft = "left",
                SidebarRight = "right"
            }
        };
        return View(page);
    }

    [HttpPost]
    public ActionResult Edit(Page page)
    {
        return View(page);
    }
}