Any updates on this?

We got the same problem. If we populate a list inside the model in the view with JQuery. We would get the data in the SurfaceController. But loose it again if the model is not valid.

For the exsample we populated 2 items in the list.

@using (Html.BeginUmbracoForm<MemberController>("Submit"))
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary()

    @* The list contains zero submembers. (But it could) *@
    @for (var i = 0; i < Model.SubMembers.Count; i++)
    {
        @Html.TextBoxFor(model => model.SubMembers[i].Name)
    }

    @* So we populate 2 here *@
    <input id="SubMembers_0__Name" name="SubMembers[0].Name" type="text" value="Jens">
    <input id="SubMembers_1__Name" name="SubMembers[1].Name" type="text" value="Per">
}

In the SurfaceController we would get these 2 populated submembers,

 [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Submit(MemberModel model)
    {
        // Contains 2. Contains Jens & Per
        var listCount = model.SubMembers.Count;

        if (!ModelState.IsValid)
        {
            // if the model is invalid. We loose the model.SubMembers in the view.
            return CurrentUmbracoPage();
        }
        return RedirectToCurrentUmbracoPage();
    }

Any pointers would be appreciate ;)

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