@model object
<div class="form-group@(Html.ValidationErrorFor(m => m, " has-error"))">
  @Html.LabelFor(m => m, new { @class = "control-label" })
  <div class="controls">
    @Html.TextBox(
      "",
      ViewData.TemplateInfo.FormattedModelValue,
      ViewBag.ClearTextField == true "form-control clear-text-field input-block-level" } : new { @class = "form-control input-block-level" } )
    @Html.ValidationMessageFor(m => m, null, new { @class = "help-block" })
  </div>
</div>

    public static MvcHtmlString ValidationError(this HtmlHelper htmlHelper, string field, string error)
    {
      if (HasError(htmlHelper, ModelMetadata.FromStringExpression(field, htmlHelper.ViewData), field))
        return new MvcHtmlString(error);
      else
        return null;
    }

    <div class="form-group@(Html.ValidationError("Department", " has-error"))">
      <label class="control-label" for="DepartmentId">所在部门</label>
      <div class="controls">
        <span id="deptname"> </span><a id="btnSelectDepartment">选择部门</a>
        <input class="form-control" data-val="true" data-val-required="部门是必需的。" id="DepartmentId" name="DepartmentId" type="hidden" value="">
        @Html.ValidationMessage("Department", null, new { @class = "help-block" })
      </div>
    </div>

//ready
      var $divuserform = $("#divuserform");
      $divuserform.dialog({
        title: '新建用户',//.....
      });
      $("#btnCreateUser").click(function () {
        var nodes = zTreeObjleft.getSelectedNodes();
        if (nodes.length > 0) {
          CreateUserForm($divuserform);
        }
      })
 
 
function CreateUserForm(form) {
      var $divuserform = form;
      $.ajax({
        url: "CreateUser",
        success: function (html) {
          CreateUserFormSuccessCallback(html, $divuserform);
        }
      });
    }
 
    function InitSelectDepartmentWhenCreateUser() {
      $("#btnSelectDepartment").departmentSelection({
        onSelected: function (name, id) {
          $("#deptname").text(name);
          $("#DepartmentId").val(id);
        }
      });
    }
 
    function CreateUserFormSuccessCallback(html, form) {
      var $divuserform = form;
      $divuserform.children().children().html(html);
      $("#divuserform").dialog("open");
      var $form = $divuserform.find("form")
      InitSelectDepartmentWhenCreateUser();
      $form.submit(function () {
        $form.ajaxSubmit(function (data) {
          if (data == "success") {
            $("#divuserform").dialog("close");
            $("#divuserform").clearForm();
          }
          else {
            CreateUserFormSuccessCallback(data, form);
          }
        });
        event.preventDefault();
      });
    }

      if (!DepartmentId.HasValue)
      {
        ModelState.AddModelError("Department", "必须选择部门");
      }
 
      if (ModelState.IsValid)
      {
        user.Id = Guid.NewGuid();
        user.CreateTime = DateTime.Now;
        if (DepartmentId.HasValue)
        {
          var dept = new DeptUserRole();
          dept.DepartmentId = DepartmentId.Value;
          dept.IsMain = true;
          dept.RoleId = RoleId.Value;
          user.DeptUserRoles.Add(dept);
        }
        db.Users.Add(user);
        await db.SaveChangesAsync();
        return Content("success");
      }
 
      return View(user);