How to use ELMAH to manually log errors

Question

Is it possible to do the following using ELMAH?

logger.Log(" something"); 

I'm doing something like this:

try  {     // Code that might throw an exception  } catch(Exception ex) {     // I need to log error here... } 

This exception will not be automatically logged by ELMAH, because it was handled.

Answer 1

Direct log writing method, working since ELMAH 1.0:

try  {     some code  } catch(Exception ex) {     Elmah.ErrorLog.GetDefault(HttpContext.Current).Log(new Elmah.Error(ex)); } 

ELMAH 1.2 introduces a more flexible API:

try  {     some code  } catch(Exception ex) {     Elmah.ErrorSignal.FromCurrentContext().Raise(ex); } 

There is a difference between the two solutions:

• Raise method applies ELMAH filtering rules to the exception. Log method does not.
• Raise is subscription based and is able to log one exception into the several loggers.

Answer 2

I'd recommend wrapping the call to Elmah in a simple wrapper class of your own.

using Elmah;  public static class ErrorLog {     /// <summary>     /// Log error to Elmah     /// </summary>     public static void LogError(Exception ex, string contextualMessage=null)     {         try         {             // log error to Elmah             if (contextualMessage != null)              {                 // log exception with contextual information that's visible when                  // clicking on the error in the Elmah log                 var annotatedException = new Exception(contextualMessage, ex);                  ErrorSignal.FromCurrentContext().Raise(annotatedException, HttpContext.Current);             }             else              {                 ErrorSignal.FromCurrentContext().Raise(ex, HttpContext.Current);             }              // send errors to ErrorWS (my own legacy service)             // using (ErrorWSSoapClient client = new ErrorWSSoapClient())             // {             //    client.LogErrors(...);             // }         }         catch (Exception)         {             // uh oh! just keep going         }     } } 

Then just call it whenever you need to log an error.

try {    ... }  catch (Exception ex)  {     // log this and continue     ErrorLog.LogError(ex, "Error sending email for order " + orderID); } 

This has the following benefits:

• You don't need to remember this slightly archaic syntax of the Elmah call
• If you have many DLLs you don't need to reference Elmah Core from every single one - and just put this in your own 'System' DLL.
• If you ever need to do any special handling or just want to put in a breakpoint to debug errors you have it all one place.
• If you ever move away from Elmah you can just change one place.
• If you have legacy error logging you want to retain (I just happen to have a simple error logging mechanism that's tied into some UIs that I dont immediately have time to remove).

Note: I've added a 'contextualMessage' property for contextual information. You can omit this if you prefer but I find it very useful. Elmah automatically unwraps exceptions so the underlying exception will still be reported in the log but the contextualMessage will be visible when you click on it.