Using complex model in MVC 2

Question

I have:
1)

public class Model
{
    public String Name { get; set; }
    public SubModel SubModel { get; set; }
}  

2)

public SubModel
{
    public String Title { get; set; }
}

3) Model-typed ModelViewUserControl
4) SubModel-typed SubModelViewUserControl
5) Page

I need:
Show on the Page 2 TextBoxes: for Model.Name and Model.SubModel.Title.

I do:
1) In Page:

<% Html.RenderPartial("ModelViewUserControl", Model); %>

2) In ModelViewUserControl:

<%= Html.TextBoxFor(m => m.Name) %>
<% Html.RenderPartial("SubModelViewUserControl", Model.SubModel); %>

3) In SubModelViewUserControl:

<%= Html.TextBoxFor(m => m.Title) %>

Result is
In Controller's method I have Model.Name == "Bla" but Model.SubModel == null. Of course, I use Html.BeginForm().

HTML:

<input id="Name" name="Name" type="text" value="" />
<input id="Title" name="Title" type="text" value="" />

Answer 1

Make sure your two action methods are using the SAME data type for the model.

Your view can display the textbox fields like this:

<%: Html.TextBoxFor(m => m.Name) %>
<%: Html.TextBoxFor(m => m.SubModel.Title) %>

If you need more help, post your action methods and your view.

Answer 2

Take the following with lots of salt. I'm still working through this stuff.

This isn't the easiest way to figure this out, but a debug method I use for these things is to change the action parameter to a FormCollection. Then I do:

        StringBuilder sb = new StringBuilder();
        foreach (string key in fc.Keys)
        {
            sb.Append("Key: " + key + " Value: " + fc[key]);
        }

And inspect the value of sb in debug. This is probably a bad time waster, but it's how I've stumbled through this so far.

The issue you're having is the model binding. The Title input element needs to be named something like [ObjectType]_[PropertyName]. I don't know why the Html.TextBoxFor is not handling that.

Answer 3

Instead of using RenderPartial I would recommend you using editor templates which will make your life easier:

In the main View:

<% using (Html.BeginForm()) { %>
    <%= Html.EditorForModel() %>
    <input type="submit" value="OK" />
<% } %>

Editor template for the model (~/Views/Shared/EditorTemplates/Model.ascx):

<%= Html.TextBoxFor(x => x.Name) %>
<%= Html.EditorFor(x => x.SubModel) %>

Editor template for the SubModel (~/Views/Shared/EditorTemplates/SubModel.ascx):

<%= Html.TextBoxFor(m => m.Title) %>