Remote validation in mvc C#

How to: Implement Remote Validation from a Client in MVC4

A remote server calls in order to validate a form field without posting the entire form to the server.
Model:

public class ForgotPasswordModel

{

    [Remote("DoesEmailExist", "Account", HttpMethod = "POST", ErrorMessage = "Your Email address was not found. Please try again.")]

    [RegularExpression(@"^([0-9a-zA-Z]([\+\-_\.][0-9a-zA-Z]+)*)+@(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]*\.)+[a-zA-Z0-9]{2,3})$", ErrorMessage = "Your email address is not in a valid format. Example of correct format: [email protected]")]

    [StringLength(100)]

    [Required]

    [DataType(DataType.EmailAddress)]

    [Display(Name = "Email address")]

    public string EmailAddress { get; set; }

}

So you want to add AdditionalFields in remote validation is very is to add other fields.
Like

[Remote("DoesEmailExist", "Account", AdditionalFields = "id", HttpMethod = "POST", ErrorMessage = "Your Email address was not found. Please try again.")]

Controller:

[AllowAnonymous]

[HttpPost]

public JsonResult DoesEmailExist(ForgotPasswordModel forgot)

{

    // return true or false, if email exist or not

    return Json(false, JsonRequestBehavior.AllowGet);

}

[AllowAnonymous]

[HttpPost]

public ActionResult ForgotPassword(ForgotPasswordModel forgotPassword)

{

    if (ModelState.IsValid)

    {

       // do you work

    }

    return View(forgotPassword);

}

View:

@model AppName.Models.ForgotPasswordModel

@{

    ViewBag.Title = "Forgot Password";

}

<script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>

<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>

@using (Html.BeginForm())

{

    @Html.LabelFor(model => model.EmailAddress)

    @Html.TextBoxFor(model => model.EmailAddress)

    @Html.ValidationMessageFor(model => model.EmailAddress)

    <input type="hidden" name="InitialEmail" value="[email protected]" />

    <input type="submit" value="Submit"/>

}

Remote validation in MVC 4 doesn't work why?

In Web.config file.
The appSettings element contains the following keys to enable client validation and enable unobtrusive JavaScript validation.

<appSettings>

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

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

</appSettings>

If you have wrong jquery url mapping. Make sure src @Url.Content("~/Scripts/jquery.validate.js") is valid.