Log File

In this article, we will adopt a simple mechanism to log errors and exceptions in website,

The error will get logged in a text file on the server.

The error file will be created on a daily basis, whenever the error is encountered

Public Shared Sub WriteErrorLog(ByVal errorMessage As String, ByVal errorStack As String, ByVal methodName As String)

Dim path As String = "~/LOG/" & DateTime.Today.ToString("dd-MM-yy") & ".txt"

If (Not File.Exists(System.Web.HttpContext.Current.Server.MapPath(path))) Then

File.Create(System.Web.HttpContext.Current.Server.MapPath(path)).Close()

End If

Using w As StreamWriter = File.AppendText(System.Web.HttpContext.Current.Server.MapPath(path))

w.WriteLine(Constants.vbCrLf & "Log DateTime : " & DateTime.Now.ToString(System.Globalization.CultureInfo.InvariantCulture))

w.WriteLine("Page :- " & System.Web.HttpContext.Current.Request.Url.AbsolutePath.ToString.Trim)

w.WriteLine("Function Name :- " & methodName)

w.WriteLine("Message :- " & errorMessage)

w.WriteLine("Stack Trace :- " & errorStack)

w.WriteLine("__________________________")

w.Flush()

w.Close()

End Using

End Sub

Protected Sub btnTest_Click(ByVal sender As Object, ByVal e As System.EventArgs)

Try

Dim i As Integer = 1

Dim j As Integer = 0

Response.Write(i \ j)

Catch ex As Exception

WriteErrorLog(ex.Message, ex.StackTrace.ToString.Trim, ex.TargetSite.Name)

End Try

End Sub

OutPut

__________________________

Log DateTime : 07/15/2009 15:25:20

Page :- /Default.aspx

Function Name :- btnTest_Click

Message :- Attempted to divide by zero.

Stack Trace :- at Default.aspx.btnTest_Click(Object sender, EventArgs e) in D:\Test\Default.aspx.vb:line 107

__________________________

Same thing you can do in Globa.asax, at Application_Error event. You can get an Server last error by Server.GetLastError()

Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)

' Code that runs when an unhandled error occurs

Dim objErr As Exception = Server.GetLastError().GetBaseException()

'Function Name not be correct at application level error

WriteErrorLog(objErr .Message, objErr .StackTrace.ToString.Trim, "")

'IF you want you can redirect to user after log into log file here

' Response.Redirect("Error.aspx")

End Sub