• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 339
  • Last Modified:

File Changed Event in VB.NET

Hi Experts, I am currently developing an application using VB.NET to keep track of any additions, modifications and deletions of all the files and subfolders of the current watched directory. I want the application to be able to log these changes to a database. How could I define an event in VB.NET to keep track of such modifications so that it could trigger a writing process to the database?

Upon completing the writing of the changed files and/or subfolders, I want to reset them back to default so that if the application is still running, I want to detect any new changes made to these files/subfolders for the current watched directory.

Please advice.

TIA.
0
bpyeo
Asked:
bpyeo
  • 4
  • 2
1 Solution
 
RonaldBiemansCommented:
Use the filesystemwatcher class

here is a code snippet from MSDN

Public Class Watcher
   
    Public Shared Sub Main()
        Dim args() As String = System.Environment.GetCommandLineArgs()
        ' If a directory is not specified, exit the program.
        If args.Length <> 2 Then
            ' Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)")
            Return
        End If
       
        ' Create a new FileSystemWatcher and set its properties.
        Dim watcher As New FileSystemWatcher()
        watcher.Path = args(1)
        ' Watch for changes in LastAccess and LastWrite times, and
        ' the renaming of files or directories.
        watcher.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)
        ' Only watch text files.
        watcher.Filter = "*.txt"
       
        ' Add event handlers.
        AddHandler watcher.Changed, AddressOf OnChanged
        AddHandler watcher.Created, AddressOf OnChanged
        AddHandler watcher.Deleted, AddressOf OnChanged
        AddHandler watcher.Renamed, AddressOf OnRenamed
       
        ' Begin watching.
        watcher.EnableRaisingEvents = True
       
        ' Wait for the user to quit the program.
        Console.WriteLine("Press 'q' to quit the sample.")
        While Chr(Console.Read()) <> "q"c
        End While
    End Sub
     
    ' Define the event handlers.
    Private Shared Sub OnChanged(source As Object, e As FileSystemEventArgs)
        ' Specify what is done when a file is changed, created, or deleted.
        Console.WriteLine("File: " & e.FullPath & " " & e.ChangeType)
    End Sub    
   
    Private Shared Sub OnRenamed(source As Object, e As RenamedEventArgs)
        ' Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath)
    End Sub
   
End Class
0
 
bpyeoAuthor Commented:
I have tried to place the above code in a class module and try to instantiate from my form. It does not work. Please advice.

TIA.
0
 
RonaldBiemansCommented:
Could to explain what doesn't work, do you get an error message, if so where and what.
0
Introducing Cloud Class® training courses

Tech changes fast. You can learn faster. That’s why we’re bringing professional training courses to Experts Exchange. With a subscription, you can access all the Cloud Class® courses to expand your education, prep for certifications, and get top-notch instructions.

 
bpyeoAuthor Commented:
I did not receive any error message. I have created a button and instantiate this object with the click event. It does not have any response. Please advice.

TIA.
0
 
RonaldBiemansCommented:
Hi bpyeo,

I see, the above code was only an example on how it works you can not implement it like you did, because it is a console application.

change it to this (put the below code in a class)

Imports System.IO
Public Class Watcher

    Sub New(ByVal dir As String)

        ' Create a new FileSystemWatcher and set its properties.
        Dim watcher As New FileSystemWatcher


        watcher.Path = dir
        ' Watch for changes in LastAccess and LastWrite times, and
        ' the renaming of files or directories.
        watcher.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)
        ' Only watch text files.
        watcher.Filter = "*.*"

        ' Add event handlers.
        AddHandler watcher.Changed, AddressOf OnChanged
        AddHandler watcher.Created, AddressOf OnChanged
        AddHandler watcher.Deleted, AddressOf OnChanged
        AddHandler watcher.Renamed, AddressOf OnRenamed

        ' Begin watching.
        watcher.EnableRaisingEvents = True

        ' Wait for the user to quit the program.
    End Sub

    ' Define the event handlers.
    Private Shared Sub OnChanged(ByVal source As Object, ByVal e As FileSystemEventArgs)
        ' Specify what is done when a file is changed, created, or deleted.
        Console.WriteLine("File: " & e.FullPath & " " & e.ChangeType.tostring)
    End Sub

    Private Shared Sub OnRenamed(ByVal source As Object, ByVal e As RenamedEventArgs)
        ' Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath)
    End Sub

End Class


and call like this

Dim x As New Watcher("c:\")

the above code now writes to the console so you will have to adjust it to your needs


I tested this and it works


0
 
RonaldBiemansCommented:
The watcher now watches all files

watcher.Filter = "*.*"

if you want it to look at only files with the extension .txt then change it to

watcher.Filter = "*.txt"

or .exe

watcher.Filter = "*.exe"

etc ..

0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Cloud Class® Course: Microsoft Azure 2017

Azure has a changed a lot since it was originally introduce by adding new services and features. Do you know everything you need to about Azure? This course will teach you about the Azure App Service, monitoring and application insights, DevOps, and Team Services.

  • 4
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now