asp.net mvc and model binding objects with sub objects - asp.net-mvc

Question

I'm trying to get model bind a sub class in a form.
I have a Page class with a related PageContent class.
There are many PageContent objects in a Page object.
ie Page.PageContents
I return Page as the Model and I can see all the PageContent items.
However I'm a bit blurry on how to assign the PageContent items to the form so it'll keep it's model binding.
When I Post the Page model back into the controller, the PageContent list is empty.
Here is a snippet of the form:
<% using (Html.BeginForm("SavePage", "Admin")) {%>
<fieldset>
<legend>Fields</legend>
<%=Html.Hidden("PageId", Model.PageId) %>
<p>
<label for="Title">Title:</label>
<%= Html.TextBox("Title", Model.Title) %>
<%= Html.ValidationMessage("Title", "*") %>
</p>
<p>
<label for="SysName">SysName:</label>
<%= Html.TextBox("SysName", Model.SysName) %>
<%= Html.ValidationMessage("SysName", "*") %>
</p>
<%
int i = 0;
foreach (var pageContent in Model.PageContents)
{ %>
<div>
<%=Html.Hidden("PageContents[" + i + "].PageContentId", pageContent.PageContentId) %>
<%=Html.TextArea("PageContents[" + i + "].Content", pageContent.Content)%>
</div>
<%
i++;
} %>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
<% } %>
I'm thinking I haven't made the PageContents aspect of the form correctly.
EDIT:
Here is the basic controller method I POST to:
public ActionResult SavePage(Page page)
{
// do stuff with page.PageContents
return View("PageEdit", page);
}
I'm not using the Request.Form style
Please help :D

Answer 1

You said Page.PageContents is an EntitySet<PageContent> and that you are using auto-generated classes. So, I guess, you are using LINQ to SQL? If so, then you can use partial classes in order to add properties to the generated class
I remember that I had a similiar problem, I wasnt able to bind to EntitySet<T> properties. I think I fixed it by using a proxy / placeholder property which was an IList<T> what effectively set the actual property. So, in your case, that would look something like this:
// Your partial class, adding a property to the generated class
public partial class Page
{
// Bind to this property
public IList<PageContent> MyPageContents
{
set
{
var set = new EntitySet<PageContent>();
set.AddRange(value);
PageContents = set;
}
get { return PageContents; }
}
}
// This and probably a lot more is created by LINQ to SQL
public partial class Page {
// ...
public EntitySet<PageContent> PageContents
{
get;
set;
}
// ...
}
I think partial classes have to be in the same namespace as the auto generated class. More info here: Adding new methods to LINQ to SQL generated classes
And then, in your form, you bind to MyPageContents (you can use a better name of course) instead of PageContents.
Hopefully it works for you, it is quite some time ago since I last used LINQ to SQL.