Getting WebApi Exception Response in an Exception Filter

Question

We installed an Exception filter

public class APIErrorHandlerAttribute : ExceptionFilterAttribute, IExceptionFilter
{
     // Sets up log4net logger
    private static readonly log4net.ILog log = log4net.LogManager.GetLogger
        (System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

    public override void OnException(HttpActionExecutedContext context)
    {
        if (context.Exception is BusinessException)
        {
            throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)
            {
                Content = new StringContent(context.Exception.Message),
                ReasonPhrase = "Exception"
            });

        }

        //Log Critical errors
        log.Info("/****************** API Begin Error ******************/");
        log.Info("Exception:" + context.Exception + "  Case:" + CaseHelper.GetCurrentCaseID() + "  UserID:" + UserHelper.GetCurrentUserID());
        log.Info("/****************** API End Error ******************/");

        throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)
        {
            Content = new StringContent(string.Format("Message: {0}\nStack Trace: {1}", context.Exception.Message, context.Exception.StackTrace)),
            ReasonPhrase = "Critical Exception",
        });
    }
}

for all WebApi routes

    //*** Log API Error Globally using Log4net
    public static void RegisterFilters(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute("DefaultApiError", "api/{controller}/{action}/{id}", new { id = RouteParameter.Optional });
        config.Filters.Add(new LRAPIErrorHandlerAttribute());
    }

We also have an authorization attribute that we attach to some controllers. It looks something like this:

public class LegalRadiusAPIAuthorizationAttribute : ActionFilterAttribute, IActionFilter, IFilter
{
    public string Permissions { get; set; }
    public string Roles { get; set; }
    public string Users { get; set; }

    public override void OnActionExecuted(HttpActionExecutedContext filterContext)
    {
        if (!HttpContext.Current.User.Identity.IsAuthenticated)
        {
            throw new HttpResponseException(HttpStatusCode.NonAuthoritativeInformation); //203
        }
     }
}

So, if an unauthenticated user hits a route that requires him to be logged in, we throw. If I debug inside this filter and open up the exception dialog I can see the following properties on the exception object:

If I look at the Response prop I see all the pertinent details of the exception thrown.

The problem is when this exception gets handled by APIErrorHandlerAttribute. By the time the exception gets to the handler I can't seem to find the Response property of the exception in context.Exception...

Even though, at the handler I get the following error message from the caught exception:

Processing of the HTTP request resulted in an exception. Please see the HTTP response returned by the 'Response' property of this exception for details.

implying that the exception in context should have that property.

I feel like I'm having scope issues and that the original exception object that was thrown in the filter isn't in the context parameter of the Exception Handler.

And if you click on the plus icon on the [System.Web.Http.HttpResponseException] ? — Hackerman
– Hackerman, Commented Dec 26, 2016 at 16:34
@Hackerman That's it! Now, how do I access [System.Web.Http.HttpResponseException] from context.Exception? — seebiscuit
– seebiscuit, Commented Dec 29, 2016 at 20:53
Just right click on it and add another watch. That is going to give you the appropiate casting in order to retrieve the info from the context :) — Hackerman
– Hackerman, Commented Dec 29, 2016 at 22:42
That did it @Hackerman! Write it up as an Answer so I can mark it as accepted :D — seebiscuit
– seebiscuit, Commented Dec 30, 2016 at 0:35

Hackerman · Accepted Answer · 2016-12-30 14:07:03Z

3

You just need to access the [System.Web.Http.HttpResponseException] from your context.Exception. In order to do that, and based on the picture, you need to right click on the [System.Web.Http.HttpResponseException] and add a watcher on it. That is going to give you the appropriate casting in order to retrieve the information from the context.

answered Dec 30, 2016 at 14:07

Hackerman

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Laughing · Accepted Answer · 2016-12-27 02:27:08Z

0

Try this var exceptionData = new ExceptionData { Name = "exception name", Message = "exception message" }; Content = new ObjectContent<ExceptionData>(exceptionData, JsonFormatter),

answered Dec 27, 2016 at 2:27

Laughing

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