Logging Exceptions Through a Base Page

["Hart, Leo" <Le...@FMR.COM>]

Hello,

I suspect this will be an easy one for you experts out there, but I
haven't been able to figure it out at this point.

I have a web application utilizing Log4Net.  I am trying to figure out
the best way to capture and log unhandled exceptions in my app.  I have
two major requirements:

1:  I don't want to have to write the same repetitive code in each new
page.
2:  I want the Logger of my log entry to contain the name of the Page
that triggered the error.


So here's what I did:

I have a class called ReferenceWebApp.Web.BasePage that inherits
System.Web.UI.Page:

	#Region " Options "

	Option Explicit On 
	Option Strict On

	#End Region

	#Region " Imports "

	Imports log4net
	Imports log4net.Config

	Imports System.Web
	Imports System.Web.SessionState
	Imports System.IO

	#End Region

	Public Class BasePage
		Inherits System.Web.UI.Page

	#Region " Member Variables "

		Protected m_log As ILog =
LogManager.GetLogger(GetType(BasePage))

	#End Region

		Protected Overridable Sub Page_Error(ByVal sender As
Object, ByVal e As System.EventArgs) Handles MyBase.Error
			Me.m_log.Error("An unexpected exception has
occurred: ", Server.GetLastError)
			Server.ClearError()
	
Server.Transfer("/ReferenceWebApp/ExceptionPages/ExceptionUnhandled.aspx
")
		End Sub

	End Class

This class acts as a base page class from which all other pages in the
application will inherit.  

I also have a class called ReferenceWebApp.Web.SimpleLoggingPage1 that
inherits from my base class:

	#Region " Options "

	Option Explicit On 
	Option Strict On

	#End Region

	#Region " Imports "

	Imports log4net

	Imports ReferenceWebApp.Data.Dtos
	Imports ReferenceWebApp.Data.Persistence.Daos

	#End Region

	Namespace LoggingUsage

		Public Class SimpleLoggingPage1
			Inherits BasePage

	#Region " Web Form Designer Generated Code "

			'This call is required by the Web Form Designer.
			<System.Diagnostics.DebuggerStepThrough()>
Private Sub InitializeComponent()

			End Sub

			'NOTE: The following placeholder declaration is
required by the Web Form Designer.
			'Do not delete or move it.
			Private designerPlaceholderDeclaration As
System.Object

			Private Sub Page_Init(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
				'CODEGEN: This method call is required
by the Web Form Designer
				'Do not modify it using the code editor.
				InitializeComponent()
			End Sub

	#End Region

			Protected WithEvents wc_btnCauseException As
Button

	#Region " Member Variables "

			Protected Shadows m_log As ILog =
LogManager.GetLogger(GetType(SimpleLoggingPage1))

	#End Region

			Private Sub Page_Load(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
				Me.m_log.Info("Info log.")

				Me.m_log.Debug("Debug log 1.")
				Me.m_log.Debug("Debug log 2.")
			End Sub

			Private Sub wc_btnCauseException_Click(ByVal
sender As System.Object, ByVal e As System.EventArgs) Handles
wc_btnCauseException.Click
				Throw New Exception("Ack!  An
exception!")
			End Sub

		End Class

	End Namespace

This works almost as I want it to.  Whenever an exception occurs,
BasePage.Page_Error gets called and a log entry is made:

	ERROR | 2005-09-01 14:52:44, 630 | 4244 |
ReferenceWebApp.Web.BasePage | Page_Error | An unexpected exception has
occurred: 
	Exception: System.Exception
	Message: Ack!  An exception!
	Source: ReferenceWebApp.Web
	   at
ReferenceWebApp.Web.LoggingUsage.SimpleLoggingPage1.wc_btnCauseException
_Click(Object sender, EventArgs e)
	   at System.Web.UI.WebControls.Button.OnClick(EventArgs e)
	   at
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.Rai
sePostBackEvent(String eventArgument)
	   at
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler
sourceControl, String eventArgument)
	   at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection
postData)
	   at System.Web.UI.Page.ProcessRequestMain()

The only problem is that the logger being used is
ReferenceWebApp.Web.BasePage and not
ReferenceWebApp.Web.SimpleLoggingPage1.  I understand WHY this is
occuring, but I was hoping you guys might have some idea how to get
around this.  I want to be able to filter on page or namespace and send
certain error messages to one person and other messages to another.


Thanks,
Leo Hart