title: dev express grid view combo box default value when binding value is null / empty
body: <p>The following is the combobox code that im using in the dev express grid view edit template.
  I want the combobox display nothing at all or a string that says "Please Choose and Employee" while adding a new employee and not when its editing.</p>
  
  <pre><code>        @Html.DevExpress().ComboBox(edtSettings =&gt;
              {
                  edtSettings.Width = 200;
                  edtSettings.Name = "EmployeeID";
                  //edtSettings.Properties.TextField = "FirstName";
                  edtSettings.Properties.ValueField = "EmployeeID";
                  edtSettings.Properties.ValueType = typeof(int);
  
                  edtSettings.Properties.DropDownStyle = DropDownStyle.DropDownList;
                  edtSettings.ShowModelErrors = true;
  
                  edtSettings.Properties.TextFormatString = "{0}" + " " + "{1}";
                  edtSettings.Properties.Columns.Add("FirstName", "First Name", 150);
                  edtSettings.Properties.Columns.Add("LastName", "Last Name", 150);
  
                  //--- For client side validations
                  edtSettings.Properties.ValidationSettings.RequiredField.IsRequired = true;
                  edtSettings.Properties.ValidationSettings.RequiredField.ErrorText = "An Employee must be selected from the list.";
  
              }).BindList(Model.NonUsers).Bind(Model.UserSingle.EmployeeID).GetHtml()
  </code></pre>
  
  <p>I do this to pass the right Model.UserSingle among other things as follows</p>
  
  <pre><code>    var User = ViewData["UserDetail"] != null
                              ? ViewData["UserDetail"]
                              : !c.Grid.IsNewRowEditing
                                  ? Model.UserList.FirstOrDefault(m =&gt; m.EmployeeID == Convert.ToInt32(DataBinder.Eval(c.DataItem, "EmployeeID")))
                                  : new User
                                      {
                                          SiteID = (int)Session["siteID"],
  
                                          ////employee ID cant set to blank, keeps adding a zero
                                          //EmployeeID = Convert.ToInt32(null),
  
                                          //this is defaulted to 'Timesheet Only'
                                          UserGroupID = 3
                                      };
  
              Model.UserSingle = (User)User;
  </code></pre>