Question

I have a situation where I need to edit an enumerable property in a view model:

public class ViewModel
{
    public MyObj Obj { get; set; }
    public IEnumerable<MyObj> MyObjs = new List<MyObj>();
}

I have followed this post; controller action:

public ActionResult Index()
{
    var viewModel = new ViewModel();
    viewModel.Obj = new Obj() { Name = "0", Value = true };
    var o1 = new MyObj() { Name = "1", Value = false };
    var o2 = new MyObj() { Name = "2", Value = false };
    viewModel.Objs = new List<Obj>() { o1, o2 };

    return View(viewModel);
}

[HttpPost]
public ActionResult Index(ViewModel viewModel)
{
    return View(viewModel);
}

The Index view as follows:

<% using (Html.BeginForm()) { %>

    <table>
        <tr>
            <th>Name</th>
            <th>Value</th>
        </tr>
        <%= Html.EditorFor(x => x.Objs) %>
    </table>

    <br />

    <input type="submit" value="Submit" />

<% } %>

And the editor template in “~/Views/Home/EditorTemplates/Obj.ascx”:

    <tr>
        <td><%: Html.TextBoxFor(x => x.Name) %></td>
        <td><%: Html.CheckBoxFor(x => x.Value) %></td>
    </tr>

The issue is: browse to Index, the data shows up. The POST, and the enumerable data disappears. Stepping through, the singular “Obj” in the view model remains, so it is just the enumerable data that is disappearing.

I have been staring at this for some time now, if any one could help out it would be brilliant.

Cheers,

Tim.

Answer 1

Take a look at this post by Phil Haack, MVC2 doesn’t natively support binding a list back to the viewmodel unless you do a little manipulation.

Update: I’ve looked into this a little more and think you should try adding TryUpdateModel(viewModel.MyObjs, "MyObjs"); to your Controller. This informs the modelbinder that it should use the “MyObjs” binding prefix to attach the data from the form to the collection in your ViewModel.