Check Username Exist or Not using JSON in MVC

This code snippet for Check Username Exist or Not using JSON in MVC.

In the model:

public class User
{
[Key]
public int UserId { get; set; }
[System.Web.Mvc.Remote("DoesUsernameExist", "Admin", HttpMethod = "POST", ErrorMessage = "Username name already exists.")]
public string Username { get; set; }
}

In the controller:

[HttpPost]
public JsonResult DoesUsernameExist(string Username)
{
var db = new ApplicationDbContext();
var data = db.Users.Where(e => e.Username.Equals(Username, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
return Json(data == null);
}

DoesUsernameExist - Action Name
Admin - Controller Name

We can pass additional fields like this -

[System.Web.Mvc.Remote("DoesUsernameExist", "Admin", AdditionalFields = "UserId", HttpMethod ="POST", ErrorMessage = "Username name already exists.")]