Getting the Id of an error in Elmah after calling .Raise()

Question

I\'m working on an MVC3 application and I\'m using Elmah to handle my error logging. What I want in my application is to carry the Elmah Id onto the custom error page as I will

Answer 1

After reading Dupin's comments it seems logical that it isn't quite possible. I tried digging around the Elmah source code and came up with a couple of alternatives that might be worth sharing.

The obvious alternative is stick with my original option of using the Logged event:

void ErrorLog_Logged(object sender, ErrorLoggedEventArgs args)
{
    string sessionId = Session.SessionID;
    Session["ElmahId_" + sessionId] = args.Entry.Id;
}

For a more direct solution it is possible to manually log the error with the following:

string errorId = Elmah.ErrorLog.GetDefault(HttpContext.Current)
    .Log(new Elmah.Error(filterContext.Exception));

However, using this approach won't hit your filters or mail module and so on.

After doing a bit of thinking and a little more searching, I came up with a new compromise. Still using the logged event but I've found a way to create a new unique key that can be passed to the view, by adding my own data to the exception.

string loggingKey = "ElmahId_" + Guid.NewGuid().ToString();
filterContext.Exception.Data.Add("LoggingKey", loggingKey);

This way I can pass the exception in my view model, which has this key value in the Data collection. The logged event would be changed to something like this:

void ErrorLog_Logged(object sender, ErrorLoggedEventArgs args)
{
    string key = args.Entry.Error.Exception.Data["LoggingKey"].ToString();
    Session[key] = args.Entry.Id;
}

Then in the view I get the key from the model to then pull the Id from the Session collection.

Answer 2

http://code.google.com/p/elmah/issues/detail?id=148#c3 is an identical request and a proposed patch on the Elmah project site

Answer 3

Maybe not very helpful but I suspect you can't get the error id at that point and you will need to use the logged event.

When you call

Elmah.ErrorSignal.FromCurrentContext().Raise(filterContext.Exception)

You're just raising the error. Depending on how you've configured ELMAH you might be logging the error or you might just send an email or a tweet.

There's no direct link between a raised error and an Id. That will only come with logging which, if you're feeling funny, you could be doing in multiple places and so creating multiple ids.

Answer 4

The solution above only works only if there is a Session object (website scenario). We needed it to work in an Azure WorkerRole, or a console / desktop app type setup. This solution will also work for web and save some session memory. There isn't a perfect solution, but one that worked for us to be able to log the error and retrieve the stored ID AND fire off an email is to:

1. Store the error using ErrorLog.Log(error) (see: Using ELMAH in a console application)
2. Raise the error skipping the logging (SQL or otherwise)

For the second part, we used the implementation of ElmahExtension given here: https://stackoverflow.com/a/2473580/476400

and REMOVED the following lines adding the logging:

(ErrorLog as IHttpModule).Init(httpApplication);
errorFilter.HookFiltering(ErrorLog);  //removed!

The entire call from our client code looks like this:

ErrorLog errorLog = ErrorLog.GetDefault(null);
errorLog.ApplicationName = "YourAppName";
Error error = new Error(ex);
string errorResult = errorLog.Log(error);
Guid errorId = new Guid(errorResult);

ex.LogToElmah(); //this is just going to send the email

You might want to call that extention method something else, like RaiseToElmahNoStorage(), or something to indicate it is skipping the storage component.