remote validation in mvc affected edit

Question

I was trying to validate the user name through remote validation in client side and it's working fine in while adding the duplicate field in create Module but now it is not allowing me to edit the record using same name it's showing me the same error which I defined for create. I tried all the possible ways but not succeeded please help me. I have followed these link but it's not working in either way.

http://stackoverflow.com/questions/4778151/asp-net-mvc-3-remote-validation-to-allow-original-value http://stackoverflow.com/questions/6407096/asp-net-mvc-3-remote-attribute-passing-3-fields

here is my code what i have tried so far .please help experts.

[Required]
        [Remote("IsUserAvailable", "User", HttpMethod = "Post", ErrorMessage = "User already exist.", AdditionalFields = "InitialUserName")]
        [RegularExpression(@"^(?![\W_]+$)(?!\d+$)[a-zA-Z0-9 ]+$", ErrorMessage = "Invalid UserName ")]
 public string UserName { get; set; }


[HttpPost]
    public JsonResult IsUserAvailable([Bind(Prefix = "User.UserName")]string UserName, string initialUserName)
    {

        var result = uDbContext.Users.FirstOrDefault(a => a.UserName == UserName);
        if (result == null)
        {
            return Json(true, JsonRequestBehavior.AllowGet);
        }
        return Json(JsonRequestBehavior.AllowGet);
    }


@model User.ViewModel.ViewModelUser
@using (Html.BeginForm())
    {
        @Html.AntiForgeryToken()
        @Html.ValidationSummary(true)
        @Html.HiddenFor(m => m.User.UserId)



                @Html.LabelFor(m.User.UserName)


               @Html.TextBoxFor(m => m.User.UserName)
                @Html.ValidationMessageFor(m.User.UserName)
                @Html.Hidden("initialUserName", Model.User)
            </div>
        </div>
}

Please help experts to complete my assignment.

Answer 1

User appears to be a complex object so

@Html.Hidden("initialUserName", Model.User)

is likely to generate something like

<input type="hidden" name="initialUserName" value="YourAssemly.User" ... />

which is not going to help with validation.

You could ignore the validation by sending back the original name using

@Html.Hidden("InitialUserName", Model.User.UserName)

@Html.Hidden("User.InitialUserName", Model.User.UserName)

and then compare the values in the controller using

public JsonResult IsUserAvailable([Bind(Prefix = "User.UserName")]string UserName, string initialUserName)

public JsonResult IsUserAvailable([Bind(Prefix = "User.UserName")]string UserName, [Bind(Prefix = "User.InitialUserName")]string initialUserName)
{
  if (UserName == initialUserName)
  {
    // Nothing has changed so signal its valid
    return Json(true, JsonRequestBehavior.AllowGet);
  }
  // Check if the user name already exists
  var result = uDbContext.Users.FirstOrDefault(a => a.UserName == UserName);
  return Json(result == null, JsonRequestBehavior.AllowGet);
}

Side note: jquery remote validation is a GET call so the [HttpPost] attribute is not necessary

Edit

After debugging both the jquery-validate.js and jquery-validate-unobtrusive.js files, it turns out that the name attribute of any AdditionalFields must include the same prefix as the property being validated, and that the [Bind(Prefix="..")] attribute is then also required on those parameters in the method (refer amendments above)

An alternative might to create a simple class to post back to, for example

public class ValidateUserNameVM
{
  public string UserName { get; set; }
  public string InitialUserName { get; set; }
}

and

public JsonResult IsUserAvailable([Bind(Prefix = "User")]ValidateUserNameVM model)
{
  if (model.UserName == model.InitialUserName)
  ....

Answer 2

Your validation function is incomplete. Put a [Required] attribute on the UserName property of your model and try this:

public JsonResult IsUserAvailable(string userName, string initialUserName)
{
   if (userName.Trim().ToLower() != (initialUserName ?? "").Trim().ToLower())
   {
       var result = YourMethodToCheckTheDatabaseForUsernameIsAvailable(userName);
       return Json(result, JsonRequestBehavior.AllowGet);
   }
   return Json(true, JsonRequestBehavior.AllowGet);
}

Answer 3

For Who Get Null in the second paramter this simple idea could help

public JsonResult IsUserNameAvailable(string Name, string EditNameIssue)
        {//it will return true if match found elese it will return false. so i add !
            if (Name == EditNameIssue)
            {
                return Json(true, JsonRequestBehavior.AllowGet);
            }
            else
            {
                return Json(!db.Employees.Any(e => e.Name == Name), JsonRequestBehavior.AllowGet);
            }
        }

Go to The Class and add string EditNameIssue to the class so it could be sent to the controller

[MetadataType(typeof(EmployeeMetaData))]
    public partial class Employee
    {

        public string EditNameIssue { get; set; }
    }

And Edit the Remote attribute to send this addtional property

[Remote("IsUserNameAvailable","Employees",ErrorMessage ="User Name Already Taken",AdditionalFields = "EditNameIssue")]
        public string Name { get; set; }

This Logic may help if you add a name to edit textbox that is already taken

public JsonResult IsUserNameAvailable(string Name, string EditNameIssue)
    {//it will return true if match found elese it will return false. so i add !
        //Edit Request  
        if (Name == EditNameIssue)
        {
            //this mean he didn't change the name
            return Json(true, JsonRequestBehavior.AllowGet);
        }
        else if (Name != EditNameIssue)
        {
            //if he change the name in the edit go and check if the new name exist 
            //note if he modify and reenter it origin name it will be also erro he has to reload
            return Json(!db.Employees.Any(e => e.Name == Name), JsonRequestBehavior.AllowGet);
        }
        else if (string.IsNullOrEmpty(EditNameIssue))
        {//this mean you came from create request as there is no EditNameIssue in this view

            return Json(!db.Employees.Any(e => e.Name == Name), JsonRequestBehavior.AllowGet);

        }
        else
        {//just for the completeness
            return Json(false, JsonRequestBehavior.AllowGet);
        }


    }