Hello everyone, in this post I'll describe how to integrate remote validation into MVC. Remote validation is the technique by which we verify particular data before publishing it to a server without posting the complete form's data. Let's look at a real-world example. In one of my projects, I had to verify that an email address didn't already exist in the database.

Remote validation was helpful in that regard because it allowed us to validate simply the user-supplied email address without submitting the rest of the data.Explanation in PracticeLet's create an MVC project and give it the appropriate name—for me, "TestingRemoteValidation"—then proceed. Let's create a model called UserModel once the project has been built. Its design will be as follows:
    public class UserModel  
    {
        [Required]
        public string UserName { get; set; }
        [Remote("CheckExistingEmail","Home",ErrorMessage = "Email already exists!")]
        public string UserEmailAddress { get; set; }
    }

Let's get some understanding of the remote attribute used, so the very first parameter “CheckExistingEmail” is the name of the action. The second parameter “Home” is referred to as controller so to validate the input for the UserEmailAddress the “CheckExistingEmail” action of the “Home” controller is called and the third parameter is the error message. Let's implement the “CheckExistingEmail” action result in our home controller.
    public ActionResult CheckExistingEmail(string UserEmailAddress)
    {
        bool ifEmailExist = false;
        try
        {
            ifEmailExist = UserEmailAddress.Equals("[email protected]") ? true : false;
            return Json(!ifEmailExist, JsonRequestBehavior.AllowGet);
        }
        catch (Exception ex)
        {
            return Json(false, JsonRequestBehavior.AllowGet);
        }
    }

For simplicity I am just validating the user input with a hard-coded value but we can call the database and determine whether or not the given input exists in the database.

Let's create the view using the defined “UserModel” and using the create scaffold template; the UI will look like:

We will get the following output if we use “[email protected]” as UserEmailAddress: