Question

I have a pretty simple MVC 2 form. It has two dropdowns, user and role. The employee dropdown passes validation, and the role dropdown does not, regardless of what I select. There is no default “empty” option although I plan to implement one, which is why I need the validation to work. It fails both client and server validation. I just can’t see why one would work and one does not!

The Form:

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

    <%:Html.ValidationSummary(true) %>
    <%:Html.EditorFor(model => model.User, new { AllEmployees = Model.AllEmployees, RoleList = Model.RoleList })%>

    <p>
        <input type="submit" value="Add New User" />
    </p>

    <% } %>

<% Html.EndForm(); %>

The Editor Template:

<tr>
    <td>
        <div class="editor-label">
            <%: Html.LabelFor(model => model.UserId) %>
            <%: Html.RequiredMarkFor(model => model.UserId) %>
        </div>   
    </td>    
    <td>    
    <div class="editor-field">
        <%: Html.DropDownListFor(model => model.UserId, new SelectList(ViewData["AllEmployees"] as IEnumerable, "UserId", "DisplayName", Model.UserId)) %>
        <%: Html.ValidationMessageFor(model => model.UserId>
    </div>    
    </td>       
</tr>     

<tr>
    <td>
        <div class="editor-label">
            <%: Html.LabelFor(model => model.AccessLevel)%>
            <%: Html.RequiredMarkFor(model => model.AccessLevel)%>
        </div>   
    </td>    
    <td>    
        <div class="editor-field">
            <%: Html.DropDownListFor(model => model.AccessLevel, new SelectList(ViewData["RoleList"] as IEnumerable, Model.AccessLevel))%>
            <%: Html.ValidationMessageFor(model => model.AccessLevel)%>
        </div>    
    </td>       
</tr> 

The Metadata:

    [DisplayName("Employee")]
    [Required(ErrorMessage = "Please select an employee.")]
    [StringLength(8, ErrorMessage = "User Id must be less than 8 characters.")]
    [DisplayFormat(ConvertEmptyStringToNull = false,
                            HtmlEncode = true)]
    [DataType(DataType.Text)]
    public object UserId { get; set; }


    // Validation rules for Access Level
    [DisplayName("Role")]
    [Required(ErrorMessage = "Please select the role for this user.")]
    [StringLength(15, ErrorMessage = "Role must be under 15 characters.")]
    [DisplayFormat(ConvertEmptyStringToNull = false,
                            HtmlEncode = true)]
    [DataType(DataType.Text)]
    public object AccessLevel { get; set; }

The Get Action:

    List<String> roles = (from o in txDB.Users
                                      select o.AccessLevel).Distinct().ToList(); 

    var viewModel = new UserViewModel
    {
        User = new User(),
        AllEmployees = empList,
        RoleList = roles
    };
    return View(viewModel);

The Post Action:

    [HttpPost]
    [AuthorizeAttribute(Roles="Administrator")]
    public ActionResult Create(User user)
    {
        if(!ModelState.IsValid)
        {
            //ModelState is invalid
            return View(new User());
        }
        try
        {
           //do stuff
        }
    }

The Required Helper Method (from Define markup for [Required] fields in View in ASP.NET MVC 2.0):

    public static string RequiredMarkFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression)
    {
        if(ModelMetadata.FromLambdaExpression(expression, helper.ViewData).IsRequired)
            return "*";
        else
            return string.Empty;
    } 

Answer 1

Post method should be as follows to get Server side validation…

[HttpPost]
[AuthorizeAttribute(Roles="Administrator")]
public ActionResult Create(User user)
{
    if(!TryUpdateModel(user))
    {
       // Model is INVALID
       return View(user);
    }
    else
    {
        // ModelState is VALID
        // Do stuff
    }
}

The else might be redundant depending on what you’re doing but that should get you going.
In the view above your <% using Html.BeginForm() %> you need

<% Html.EnableClientValidation(); %>

You also need to reference the scripts, MicrosoftAjax and MicrosoftMvcValidation I think