Question

How to make it work without hard coding.

@foreach (var item in Model.Items)
{   
   //not working - it's assigning blank value
   @Html.HiddenFor(o => o.ItemIds, new { @value = item.Value.ToString() })
   //working
   @Html.Hidden("ItemIds", item.Value);
}

Answer 1

You could change your Model.Items declaration from an IEnumerable to an List, then reference your item via the index like so:

@Html.HiddenFor(o => o.Items[Model.Items.IndexOf(item)].Value)