Question

How to client side validate the dropdownlist box…..

            @Html.DropDownListFor(per => per.Gender, new[] {
                        new SelectListItem(){Text = "Male" , Value="Male"},
                        new SelectListItem(){Text ="Female" , Value = "Female"},
                    }, "Select Your Gender")
            @Html.ValidationMessageFor(per => per.Gender)

Answer 1

Include jquery validate plugin scripts in your view along with jQuery (if not already refered in the Layout.cshtml)

@model SomeModel
<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>    
@using (Html.BeginForm())
{

   @Html.DropDownListFor(per => per.Gender, new[] {
                        new SelectListItem(){Text = "Male" , Value="Male"},
                        new SelectListItem(){Text ="Female" , Value = "Female"},
                    }, "Select Your Gender")
            @Html.ValidationMessageFor(per => per.Gender)

    <input type="submit" />
}

And make sure the SomeModel’s Gender property is required

[Required]
public string Gender { set;get;}

Update your web.config to and set the AppSetting called ClientValidationEnabled to true

<appSettings>
  <add key="ClientValidationEnabled" value="true" />
  <add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>

Now when you submit, it will execute the client side validation, if javascript is enabled in the browser.