Question

Razor:

@Html.TextBoxFor(kod => kod.Name)
@Html.ValidationMessage("Name","Client Error Message")

Controller:

[HttpPost]
    public JsonResult JsonAddCustomer(Customers customer, string returnUrl)
    {
        if (customer.Name.Trim().Length == 0)
        {
            ModelState.AddModelError("Name", "Server Error Message");
        }

        //Eğer hata yoksa veri tabanına kayıt yapılıyor.
        if (ModelState.IsValid)
        {
            try
            {
                CusOpp.InsertCustomer(customer);
                return Json(new { success = true, redirect = returnUrl });
            }
            catch (Exception e)
            {
                ModelState.AddModelError("", "Error");
            }
        }

        return Json(new { errors = GetErrorsFromModelState() });
    }

I want to write validation error message. I did this like above, but @Html.ValidationMessage("Name","Client Error Message") does not work. In fact, I was already expecting it.

I want to show like this statement’s result: @Html.ValidationMessageFor(m => m.name) ,but I cant use this, because I used entity-data-model.

Should I add [Required] statement to data-model classes or any way that I do this. Sorry for bad explanation.

Thanks.

Answer 1

You should return PartialViews instead of JSON in this case. Only in the case of success you could return JSON:

[HttpPost]
public ActionResult JsonAddCustomer(Customers customer, string returnUrl)
{
    // Warning: the following line is something horrible => 
    // please decorate your view model with data annotations or use
    // FluentValidation.NET to validate it. 
    // Never write such code in a controller action.
    if (customer.Name.Trim().Length == 0)
    {
        ModelState.AddModelError("Name", "Server Error Message");
    }

    //Eğer hata yoksa veri tabanına kayıt yapılıyor.
    if (ModelState.IsValid)
    {
        try
        {
            CusOpp.InsertCustomer(customer);
            return Json(new { success = true, redirect = returnUrl });
        }
        catch (Exception e)
        {
            ModelState.AddModelError("", "Error");
        }
    }

    return PartialView(customer);
}

Now inside the success callback of your AJAX request you can test whether the POST action succeeded or not:

success: function(result) {
    if (result.redirect) {
        // we are in the success case => redirect
        window.location.href = result.redirect; 
    } else {
        // a partial view with the errors was returned => we must refresh the DOM
        $('#some_container').html(result);

        // TODO: if you are using unobtrusive client side validation here's 
        // the place to call the $.validator.unobtrusive.parse("form"); method in order 
        // to register the unobtrusive validators on the newly added contents
    }
}

Here’s a similar post that you might also read through.