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c#asp.net-mvcasp.net-mvc-3
Dismissile
Dismissile

Reputation: 33071

ASP.net MVC - Custom HandleError Filter - Specify View based on Exception Type

I am inheriting the HandleErrorAttribute in my MVC application so I can log the error:

public class HandleAndLogErrorAttribute : HandleErrorAttribute
{
    public override void OnException(ExceptionContext filterContext)
    {
        base.OnException(filterContext);

        if( filterContext.Exception != null )
        {
            // log here
        }
    }
}

I'm adding this as a global filter:

public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
    filters.Add(new HandleAndLogErrorAttribute());
}

Is it possible to specify a custom view for specific exception types as well? For example:

if( filterContext.Exception is DivideByZeroException )
{
    // how do i specify that the view should be DivideByZero?
}

Upvotes: 42

Views: 40868

Answers (1)

jgauffin
jgauffin

Reputation: 101140

  1. Create a new filter which inherits HandleErrorAttribute (or implements IExceptionFilter directly)
  2. Register it in global.asax (by replacing filters.Add(new HandleError());):

Here is a filter that I've created that tries to find a view per specific HTTP status code:

public class MyErrorHandler : FilterAttribute, IExceptionFilter
{
    public void OnException(ExceptionContext filterContext)
    {
        if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
            return;

        var statusCode = (int) HttpStatusCode.InternalServerError;
        if (filterContext.Exception is HttpException)
        {
            statusCode = filterContext.Exception.As<HttpException>().GetHttpCode();
        }
        else if (filterContext.Exception is UnauthorizedAccessException)
        {
            //to prevent login prompt in IIS
            // which will appear when returning 401.
            statusCode = (int)HttpStatusCode.Forbidden; 
        }
        _logger.Error("Uncaught exception", filterContext.Exception);

        var result = CreateActionResult(filterContext, statusCode);
        filterContext.Result = result;

        // Prepare the response code.
        filterContext.ExceptionHandled = true;
        filterContext.HttpContext.Response.Clear();
        filterContext.HttpContext.Response.StatusCode = statusCode;
        filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
    }

    protected virtual ActionResult CreateActionResult(ExceptionContext filterContext, int statusCode)
    {
        var ctx = new ControllerContext(filterContext.RequestContext, filterContext.Controller);
        var statusCodeName = ((HttpStatusCode) statusCode).ToString();

        var viewName = SelectFirstView(ctx,
                                       "~/Views/Error/{0}.cshtml".FormatWith(statusCodeName),
                                       "~/Views/Error/General.cshtml",
                                       statusCodeName,
                                       "Error");

        var controllerName = (string) filterContext.RouteData.Values["controller"];
        var actionName = (string) filterContext.RouteData.Values["action"];
        var model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);
        var result = new ViewResult
                         {
                             ViewName = viewName,
                             ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
                         };
        result.ViewBag.StatusCode = statusCode;
        return result;
    }

    protected string SelectFirstView(ControllerContext ctx, params string[] viewNames)
    {
        return viewNames.First(view => ViewExists(ctx, view));
    }

    protected bool ViewExists(ControllerContext ctx, string name)
    {
        var result = ViewEngines.Engines.FindView(ctx, name, null);
        return result.View != null;
    }
}

Upvotes: 75

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