jQuery Validate, ASP.NET MVC ModelState Errors (Async POST)

Question

I\'m developing a web app with asp.net mvc 3 and I have some form that POST to an async action (via ajax). This action recives a ViewModel with some data annotations to validate

Answer 1

You could return the ModelState errors. This is untested, but something like this should work.

return Json(new
            {
                success = false,
                errors = ModelState.Keys.SelectMany(k => ModelState[k].Errors)
                                .Select(m => m.ErrorMessage).ToArray()
            });

Edit: To display the errors in a view you just check to see if you were successful, and if not, iterate over the list of errors and put them where you show your errors.

if(!result.success) {
    for(var error in result.errors) {
        $('#errorMessages').append(error + '
');
    }
}

I prefer Darin's answer for most projects, but your consumer may not always be your own application in which case returning a list of errors is more appropriate since it would allow the consumer to display the errors however they want.