How to Write Transaction Log File in VB.NET

One of the most important and commonly ignored functionality that every application should have is the ability to track user activities and application's exceptions and then store it in a log file. On this article, I will share a simple project that will demonstrate how to add a activity/transaction logger on your VB project. The sample project I used here was created using VB.NET 2008, but all the code should also work on earlier Visual Studio 2005 version and the latest Visual Studio 2010.


To add activity logging feature on your VB.NET application, follow these steps:
1. Add an application settings item with a name of "LogPath" and type as string. This setting will hold the path of the log file to be created. (To add a setting, just double click "My Project" from the solution explorer and then click Settings from the tabs on the left.)
2. Add a textbox on the form you want to add the transaction logger. On my sample project, I named it as "txtLogs".
3. Include the following namespace.

Imports System.IO
Imports LogFileSample.My 'To access the project settings

4. Copy and Paste the following functions.

    ''' 

    ''' Write the transaction/activity on the textbox
    ''' 
    ''' the message you want to log
    ''' color to use
    ''' 
    Private Sub WriteLog(ByVal msg As String, ByVal iColor As Color)
        logcount = logcount + 1
        txtLogs.SelectionColor = iColor
        txtLogs.AppendText("[" + DateTime.Now.ToString() + "] " & msg & vbNewLine)
        If Not txtLogs.Focused Then txtLogs.Focus()
    End Sub
    ''' 

    ''' Save the transaction logs from the textbox to a log file
    ''' 
    ''' 
    Private Sub SaveLog()
        If MySettings.Default.LogPath.Length > 0 Then
            Try

                txtLogs.SaveFile(MySettings.Default.LogPath & "\" & Format(DateTime.Now, "M-d-yy h.mtt") & ".log")
                txtLogs.Clear()
                WriteLog("Log was successfully saved at " & MySettings.Default.LogPath & "\" & Format(DateTime.Now, "M-d-yy h.mtt") & ".log", Color.DarkBlue)

            Catch ex As Exception

                WriteLog("Error saving log...", Color.Red)

            End Try

        End If
    End Sub

5. Now to display a transaction on the textbox we added earlier, call WriteLog and to save it as log file, invoke the SaveLog function.

    Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        WriteLog("Log Sample Project Started", Color.Black)
    End Sub

    Private Sub btnSaveLog_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSaveLog.Click
        SaveLog()
    End Sub

Download the VB.NET (2008) sample project via [mediafire]

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