I am lost on this MVC project I am working on. I also read Brad Wilsons article. http://bradwilson.typepad.com/blog/2010/01/input-validation-vs-model-validation-in-aspnet-mvc.html

I have this:

    public class Employee
    {
        [Required]
        public int ID { get; set; }
        [Required]
        public string FirstName { get; set; }
        [Required]
        public string LastName { get; set; }
    }

and these in a controller:

     public ActionResult Edit(int id)
        {
            var emp = GetEmployee();
            return View(emp);
        }

        [HttpPost]
        public ActionResult Edit(int id, Employee empBack)
        {
            var emp = GetEmployee();
            if (TryUpdateModel(emp,new string[] { "LastName"})) {
                Response.Write("success");
            }
            return View(emp);
        }

        public Employee GetEmployee()
        {
            return new Employee {
               FirstName = "Tom",
               LastName = "Jim",
               ID = 3
            };
        }

and my view has the following:

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

    <fieldset>
        <legend>Fields</legend>    
        <div class="editor-label">
            <%= Html.LabelFor(model => model.FirstName) %>
        </div>
        <div class="editor-field">
            <%= Html.DisplayFor(model => model.FirstName) %>
        </div>

        <div class="editor-label">
            <%= Html.LabelFor(model => model.LastName) %>
        </div>
        <div class="editor-field">
            <%= Html.TextBoxOrLabelFor(model => model.LastName, true)%>
            <%= Html.ValidationMessageFor(model => model.LastName) %>
        </div>
        <p>
            <input type="submit" value="Save" />
        </p>
    </fieldset>

<% } %>

Note that the only field editable is the LastName. When I postback, I get back the original employee and try to update it with only the LastName property. But but I see on the page is the following error:

•The FirstName field is required.

This from what I understand, is because the TryUpdateModel failed. But why? I told it to update only the LastName property.

I am using MVC2 RTM

Thanks in advance.