Вы можете написать собственный фильтр действий:
public class HandleJsonErrors : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var modelState = (filterContext.Controller as Controller).ModelState;
if (!modelState.IsValid)
{
// if the model is not valid prepare some JSON response
// including the modelstate errors and cancel the execution
// of the action.
// TODO: This JSON could be further flattened/simplified
var errors = modelState
.Where(x => x.Value.Errors.Count > 0)
.Select(x => new
{
x.Key,
x.Value.Errors
});
filterContext.Result = new JsonResult
{
Data = new { isvalid = false, errors = errors }
};
}
}
}
и затем запустить его в действие.
Модель:
public class MyViewModel
{
[StringLength(10, MinimumLength = 5)]
public string Foo { get; set; }
}
Контроллер:
public class HomeController : Controller
{
public ActionResult Index()
{
return View();
}
[HttpPost]
[HandleJsonErrors]
public ActionResult Index(MyViewModel model)
{
// if you get this far the model was valid => process it
// and return some result
return Json(new { isvalid = true, success = "ok" });
}
}
и, наконец, запрос:
$.ajax({
url: '@Url.Action("Index")',
type: 'POST',
contentType: 'application/json; charset=utf-8',
data: JSON.stringify({
foo: 'abc'
}),
success: function (result) {
if (!result.isvalid) {
alert(result.errors[0].Errors[0].ErrorMessage);
} else {
alert(result.success);
}
}
});