It seems like if an Exception occurs inside a controller, the view-engine won't go to the intended view, even if the "exception" is caught inside a try-catch block?
or I'm missing something here:
public ActionResult MyController(int? param1, DateTime? param2)
{
MyModel model = new MyModel();
try
{
model = new MyModel();
//AN ERROR HAPPENS HERE (so the code goes to catch the Exception):
model.Connection.Initialize();
}
catch (Exception ex)
{
ViewBag.ErrorMessage = ex.Message;
}
//when I put a break point I get to this following line, however, "MyView" is never displayed!?
return PartialView("MyView", model);
}
You might be getting another exception afterwards, somewhere in your view. Look at the stack trace that displays on the browser page and fix that.
Related
Im working on a asp.net core website and im trying to make som global validation exception handling using Filters. The backend can at random places throw fluentapi ValidationException and I want to catch these and show the error messages to the user. This filter only cares about ValidationExceptions. All other exceptions will be handled later..
Instead of using a try/catch in every post action in all my controllers, I want to use a filter that catches only ValidationExceptions, add the errors to the ModelState and then return to the original view with the updated ModelState.
I have tried many things but every time I just get a blank page after the filter finishes. I can easily set a new RedirectToRouteResult witht the controller and action from the context. But then I dont have the ModelState and values the user entered..
public class PostExceptionFilter : ExceptionFilterAttribute
{
public override void OnException(ExceptionContext context)
{
if (context.Exception is FluentValidation.ValidationException)
{
var ex = context.Exception as FluentValidation.ValidationException;
context.Exception = null;
context.HttpContext.Response.StatusCode = 200;
context.ExceptionHandled = true;
foreach (var item in ex.Errors.ToList())
{
context.ModelState.AddModelError(item.PropertyName, item.ErrorMessage);
}
// Done with the stuff I want.
// Now please go back to the original view with the updated modelstate and values
}
else if (context.Exception is UnauthorizedAccessException)
{
// Do something else...
}
else
{
// Do something else...
}
base.OnException(context);
}
}
You cannot access the particlar Model(related to Action Method) in Exception Filters. So you have to handle the error at Controller level if you want to add Errors to model.
try
{
//Do something
}
Catch(Exception e)
{
ModelState.AddModelError(string key, string errorMessage);
Return View(model)
}
The error message will present itself in the <%: Html.ValidationSummary() %> in your View
Without try-catch blocks you won't know if exception occured in Action Method, So that you can add Custom Errors to Model.
i am unable to end response in case of some condition
eg below (in Upload Action Method), if Logerror method invoked i just want to return view(browser) without further action. i.e return from Upload Action Method.
Plase find modified question what i am trying to achive,
In case of error i want to return view by stopping all further opeartion
public ActionResult Index()
{
return View();
}
public ActionResult Upload()
{
int i=1;
DoSomethingFirst();
//if LogError i dont want execute code below, rather it should end responce
//should not reach here
string s="This should not be executed in case of LogError()";
return View("Index");
}
public void DoSomethingFirst()
{
try{
DoSomethingSecond();
}
catch(exception ex)
{
LogError();
}
}
public void DoSomethingSecond()
{
try{
DoSomethingThird();
}
catch(exception ex)
{
LogError();
}
}
public void DoSomethingThird()
{
try{
DoSomethingother();
}
catch(exception ex)
{
LogError();
}
}
private LogError()
{
Viewbag.Error="Error details";
return View("Index");
}
This doesn't return a result from the current method:
DoSomething();
But this does:
return DoSomething();
If you want to end execution of the current method, you need to do something which exits the method. Basically, either return from the method or throw an exception. Since DoSomething returns a result, presumably you want to return that result. So simply add a return statement when invoking the method.
i tried wit RedirectToAction("Index");
Same issue. You'd need to return the result:
return RedirectToAction("Index");
Edit: Based on your edit to the question, the overall concept still remains. Focusing on this part of your code here:
var s = DoSomethingFirst();
//if true i dont want execute code below, rather it should end responce
//should not reach here
In order to exit the method, any method in C#, you need to either return or throw. So the first question is... Which do you want to do here? If you want to return a redirect, for example, then return a redirect:
return RedirectToAction("SomeAction");
If you want to return the default view, return that:
return View();
If you want to throw an exception:
throw SomeException("Some Message");
The choice is yours. You just need to define:
What you want this method to return or throw under this condition.
How will you know the condition.
For that second point, your code comment says:
//if true ...
Does this mean DoSomethingFirst() returns a bool indicating success or failure? Then that would be a simple if statement:
if (!DoSomethingFirst())
return View();
Another Edit: Based on your comment below:
Inside LogError mehod called by any child method in action method, i want to update view with error message and end the operation without further operation
How will your Update method know that something it invoked internally called LogError()? What information does DoSomethingFirst() return to indicate this fact? Currently it doesn't. Your various DoSomething methods are all swallowing exceptions, which means they are internally handling exceptions so that consuming code doesn't know about them.
If you want consuming code to know about an exception, re-throw that exception. For example:
public void DoSomethingFirst()
{
try
{
DoSomethingSecond();
}
catch(exception ex)
{
LogError();
throw; // <-- this will re-throw ex without modifying it
}
}
This returns information from DoSomethingFirst(), specifically the fact that an error occurred. Your consuming code can then check for that error:
try
{
DoSomethingFirst();
}
catch (Exception ex)
{
// You should *probably* do something with ex too. So far all of your "logging" has been ignoring the actual error.
return View();
}
Regardless of the structure you build, the basics don't change. In order for consuming code to know something about the code it invokes, that invoked code has to expose that information. In order to end execution of a method, you have to either return or throw. Don't hide exceptions from consuming code if you want consuming code to respond to those exceptions.
When I try to propagate an exception and pass it as parameter into my ErrorController, it is always null.
Controller
public ActionResult Test()
{
try
{
throw new Exception("ALGO");
//
return View();
}
catch (Exception ex)
{
return RedirectToAction("Error", "Error",
new
{
exception = ex,
controller = this.ControllerContext.RouteData.Values["controller"],
action = this.ControllerContext.RouteData.Values["action"]
});
}
}
ErrorController
public ActionResult Error(Exception exception, string controller, string action)
{
// exception is always null...
Response.StatusCode = 500;
ViewBag.exception = new HandleErrorInfo(exception, controller, action);
return View();
}
Any idea how to get the exception properly?
Is there a better approach for error handling?
I also tried this one but I got several errors because of parameteless constructor for handleerrorinfo
Whenever you use RedirectToAction, it performs an HTTP redirect. Any of the values you pass have to be primitive types, since they will be appended to the redirect URL. That means that you cannot pass an entire object, like you are trying to do with the exception. The easiest thing that you can do is to replace the RedirectToAction with
return Error(ex, this.ControllerContext.RouteData.Values["controller"], this.ControllerContext.RouteData.Values["action"]);
This approach will still call your Error method and display the View properly, but it will not change the URL like a redirect would. If you wanted to use this method, then you could try using javascript to change the URL.
Also, do you really want to display all of the error details to your end user? If you are just using this to display a plain error page without details then you could look into simply using the customErrors attribute in your web config to redirect to an error page. That way all that your end user knows is that some error occured.
I have a Delete action something along this lines - abridged for this question:
[HttpGet]
public ActionResult Delete(int id)
{
var skill = _applicantSkillService.ReadApplicantSkill(id);
try
{
_applicantSkillService.DeleteApplicantSkill(skill);
}
catch (Exception ex)
{
return View(model);
}
}
Now my main concern in setting an error message in the view without building the whole view model again. Is there any way I can do this?
My second concern I have just noticed is this action method requires a view return, and the view requires a non-null model. What 'escape routes' do I have here?
You can place your error message in ViewData or TempData object and print it on view
like
#ViewData["err"].ToString()
Alternatively you can make a property of error message on your model and assign it before returning view like
model.Errormsg="your message";
I´m trying to redirect to an action from one controller to another if something in a try-block goes wrong. What I want to achieve is a general way of presenting a view to the user if something goes wrong in different controllers by directing all errors to an errorhandling ActionResult in my Homecontroller. This is basically what the code looks like:
try
{
Code that may go wrong
}
catch (Exception e)
{
set the errorcode (integer)
Logg the error (write a simple textfile)
RedirectToAction("ErrorHandling", "Home", errorcode);
}
And in the Homecontroller i would like to generate a view, telling the user that something went wrong:
public ActionResult ErrorHandling(int errorcode)
{
do something with the errorcode
return View(different view depending on errorcode);
}
My problem is that if i manipulate the code so that an exception is thrown every step in the catcblock is executed except for the RedirectToAction whic is being ignored. What am i missing? I´m kind of new to this, so hopefully there is a simple answer that i haven´t been able to find...
In your catch block try
return new RedirectToRouteResult(new RouteValueDictionary
{
{"Controller", "Home"},
{"Action", "ErrorHandling"},
{"errorcode", errorcode}
});
Maybe you simply forgot the return in your code:
return RedirectToAction("ErrorHandling", "Home", errorcode);