To create an error log file in ASP.NET

To create an error log file and write the exception details. First of all, what all data needs to be written in the file. Generally we write - date time, exception description, file in which it occured and line number. We define this method in a generic class, say, LogReport.cs and define a static method writeLog (given below). Now whenever an exception occurs we catch it and in catch block call this method as shown:

public void somefunction()
{
try
{
        //  Do something that throws an exception
}
catch(Exception ex)
{
      LogReport.WriteLog(ex);  //as WriteLog is a static method no need to create object
}
}


Below given method create a log file in App_data folder with today's date and .log extension. And then it writes the exception message, its source and stack trace into this file.

public static void WriteLog(Exception ex)
{

String LogFilePath = HttpContext.Current.Server.MapPath("~/App_Data");

try
{
         if (!Directory.Exists(LogFilePath.ToString() + "/Error_Log"));
        {
            Directory.CreateDirectory(LogFilePath.ToString() + "/Error_Log");
         }

String FileName = System.DateTime.Now.ToString("dd-MM-yyyy");
StreamWriter LogWriter = File.AppendText(LogFilePath.ToString() + "\\Error_Log\\" + FileName.ToString() + ".log");
LogWriter.WriteLine(System.DateTime.Now + " - " + ex.Source.ToString() + " - " + ex.Message.ToString() + " - " + ex.StackTrace.ToString());
LogWriter.Close();
}
catch (Exception egEx)
{
               ClsException.WriteLog(egEx);
}
}