How to display exceptions in the same View? - asp.net-mvc

Question

I search for a generic way to display thrown exceptions without redirecting to an error page but displaying it in the same view. I tried these below:
1) I firstly tried to handle them by adding a custom filter in global.asax and overriding public override void OnException(ExceptionContext filterContext) in my Attribute class but in that way, I couldn't fill filterContext.Result in the way I want since the old model of the view is not reachable so I could only redirect to an error page but that's not what I want.
2) Then I tried to catch the exceptions on my BaseController(All of my controllers inherits from it). I again override public override void OnException(ExceptionContext filterContext) in my controller and put exception details etc. in ViewBag and redirected the page to the same view by filterContext.HttpContext.Response.Redirect(filterContext.RequestContext.HttpContext.Request.Path ); but ViewBag contents are lost in the redirected page so I can't think any other way?
How can I achieve that? Code Sample that I wrote in my BaseController is below:
protected override void OnException(ExceptionContext filterContext) {
var controllerName = (string)filterContext.RouteData.Values["controller"];
var actionName = (string)filterContext.RouteData.Values["action"];
//filterContext.Result = new ViewResult
//{
// ViewName = actionName,
// ViewData = new ViewDataDictionary<??>(??),
// TempData = filterContext.Controller.TempData,
//};
filterContext.ExceptionHandled = true;
filterContext.HttpContext.Response.Clear();
filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
ModelState.AddModelError("Error", filterContext.Exception.Message);
ViewBag.das = "dasd";
filterContext.HttpContext.Response.Redirect(filterContext.RequestContext.HttpContext.Request.Path);
}

Answer 1

Maybe you could set a property in your BaseController class to have the name of the view that you want to use, setting that in whatever controller action handles the request. Then in OnException() you could have a method, that redirects to a controller action, that just returns a View that corresponds to the view name? Each controller action would have to set a default view name before it does anything else because only it knows what view it will call if any, and what view it likely was invoked by.
You'd need some sort of BaseController action that returns the new View.
The route(s) may or many not need configuration to have some sort of optional parameter(s) that you could set to be what error information you want to send to your view. For example, in the default route:
routes.MapRoute(RouteNames.Default,
"{controller}/{action}/{id}",
new {controller = "Home", action = "Index", id = "", errorInfo = UrlParameter.Optional}
BaseController:
protected ActionResult ErrorHandler()
{
ViewBag.das = (string)filterContext.RouteData.Values["errorInfo"];
return View(ViewName);
}
protected string ViewName { get; set; }
protected void GoToErrorView(ExceptionContext context, string exceptionData)
{
var actionName = "ErrorHandler";
var newVals = new RouteValueDictionary();
newVals.Add("errorInfo", exceptionData);
this.RedirectToAction(actionName, newVals);
}
In BaseController.OnException():
// ...
filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
ModelState.AddModelError("Error", filterContext.Exception.Message);
// anything else you need to do to prepare what you want to display
string exceptionData = SomeSortOfDataYouWantToPassIntoTheView;
this.GoToErrorView(filterContext, exceptionData);
}
In the specific controllers that inherit from BaseController that are returning an ActionResult specifically a ViewResult:
[HttpGet]
public ActionResult Index()
{
ViewName = <set whatever view name you want to here>
// code here, including preparing the Model
// ...
var model = new MyViewModel();
model.SomethingIWantToGiveTheView = someDataThatItNeeds;
// ...
return View(<model name>, model);
}

Answer 2

I found the solution a while ago and add the solution so that it may help the others. I use TempData and _Layout to display errors:
public class ErrorHandlerAttribute : HandleErrorAttribute
{
private ILog _logger;
public ErrorHandlerAttribute()
{
_logger = Log4NetManager.GetLogger("MyLogger");
}
public override void OnException(ExceptionContext filterContext)
{
if (filterContext.ExceptionHandled)
{
return;
}
if (!ExceptionType.IsInstanceOfType(filterContext.Exception))
{
return;
}
// if the request is AJAX return JSON else view.
if (filterContext.HttpContext.Request.Headers["X-Requested-With"] == "XMLHttpRequest")
{
filterContext.Result = new JsonResult
{
JsonRequestBehavior = JsonRequestBehavior.AllowGet,
Data = new
{
error = true,
message = filterContext.Exception.Message
}
};
filterContext.HttpContext.Response.StatusCode = 500;
}
// log the error using log4net.
_logger.Error(filterContext.Exception.Message, filterContext.Exception);
filterContext.ExceptionHandled = true;
filterContext.HttpContext.Response.Clear();
filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
if (filterContext.HttpContext.Request.Headers["X-Requested-With"] != "XMLHttpRequest")
{
if (filterContext.Controller.TempData["AppError"] != null)
{
//If there is a loop it will break here.
filterContext.Controller.TempData["AppError"] = filterContext.Exception.Message;
filterContext.HttpContext.Response.Redirect("/");
}
else
{
int httpCode = new HttpException(null, filterContext.Exception).GetHttpCode();
switch (httpCode)
{
case 401:
filterContext.Controller.TempData["AppError"] = "Not Authorized";
filterContext.HttpContext.Response.Redirect("/");
break;
case 404:
filterContext.Controller.TempData["AppError"] = "Not Found";
filterContext.HttpContext.Response.Redirect("/");
break;
default:
filterContext.Controller.TempData["AppError"] = filterContext.Exception.Message;
//Redirect to the same page again(If error occurs again, it will break above)
filterContext.HttpContext.Response.Redirect(filterContext.RequestContext.HttpContext.Request.RawUrl);
break;
}
}
}
}
}
And in Global.asax:
protected void Application_Error(object sender, EventArgs e)
{
var httpContext = ((MvcApplication)sender).Context;
var ex = Server.GetLastError();
httpContext.ClearError();
httpContext.Response.Clear();
httpContext.Response.StatusCode = ex is HttpException ? ((HttpException)ex).GetHttpCode() : 500;
httpContext.Response.TrySkipIisCustomErrors = true;
var routeData = new RouteData();
routeData.Values["controller"] = "ControllerName";
routeData.Values["action"] = "ActionName";
routeData.Values["error"] = "404"; //Handle this url paramater in your action
((IController)new AccountController()).Execute(new RequestContext(new HttpContextWrapper(httpContext), routeData));
}