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Update ComboBox list in Realtime [duplicate]

Is there some mechanism by which I can be notified (in C#) when a file is modified on the disc?

You can use the FileSystemWatcher class.
public void CreateFileWatcher(string path)
{
// Create a new FileSystemWatcher and set its properties.
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = path;
/* Watch for changes in LastAccess and LastWrite times, and
the renaming of files or directories. */
watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName | NotifyFilters.DirectoryName;
// Only watch text files.
watcher.Filter = "*.txt";
// Add event handlers.
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.Deleted += new FileSystemEventHandler(OnChanged);
watcher.Renamed += new RenamedEventHandler(OnRenamed);
// Begin watching.
watcher.EnableRaisingEvents = true;
}
// Define the event handlers.
private static void OnChanged(object source, FileSystemEventArgs e)
{
// Specify what is done when a file is changed, created, or deleted.
Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
}
private static void OnRenamed(object source, RenamedEventArgs e)
{
// Specify what is done when a file is renamed.
Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
}

That would be System.IO.FileSystemWatcher.

Use the FileSystemWatcher. You can filter for modification events only.

Check for the file system watcher in C#

I have written this code for watching files in my system, but its not alerting any modificationms in the folder or file. How can I achieve this? I am not understanding as it does not show any exceptions or errors.
static void Main(string[] args)
{
FileSystemWatcher();
}
public static void FileSystemWatcher()
{
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = #"D:\watcher";
watcher.NotifyFilter = NotifyFilters.LastWrite;
watcher.Filter = "*.*";
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.EnableRaisingEvents = true;
Console.Read();
}
private static void OnChanged(object sender, FileSystemEventArgs e)
{
Console.WriteLine(e.Name + " has changed");
}

I updated the code. The NotifyFilter needs to be expanded if you want to see new files added
static void Main(string[] args)
{
FileSystemWatcher();
}
public static void FileSystemWatcher()
{
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = #"D:\temp";
watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName | NotifyFilters.DirectoryName;
watcher.Filter = "*.*";
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += Watcher_Created;
watcher.Renamed += Watcher_Renamed;
watcher.EnableRaisingEvents = true;
Console.Read();
}
private static void Watcher_Renamed(object sender, RenamedEventArgs e)
{
Console.WriteLine(e.Name + " has been renamed");
}
private static void Watcher_Created(object sender, FileSystemEventArgs e)
{
Console.WriteLine(e.Name + " has been added");
}
private static void OnChanged(object sender, FileSystemEventArgs e)
{
Console.WriteLine(e.Name + " has changed");
}

FileSystemWatcher.NotifyFilter Property
watcher.NotifyFilter <- is flag enum!
You need to write:
watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName | NotifyFilters.DirectoryName;
...
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.Deleted += new FileSystemEventHandler(OnChanged);
watcher.Renamed += new RenamedEventHandler(OnRenamed);

FileSystemWatcher Events Not Firing

My FileSystemWatcher isn't throwing any events. I've looked at these similar questions, none seem to be an answer for my problem:
*Edit: My goal is to capture when an XLS file is copied to or created in a directory.
Filesystemwatcher doesn't trigger event
FileSystemWatcher - event not firing the second time
FileSystemWatcher Changed event doesn't fire
FileSystemWatcher - only the change event once firing once?
Monitor class:
public class Monitor
{
FileSystemWatcher watcher = new FileSystemWatcher();
readonly string bookedPath = #"\\SomeServer\SomeFolder\";
public delegate void FileDroppedEvent(string FullPath);
public event FileDroppedEvent FileDropped;
public delegate void ErrorEvent(Exception ex);
public event ErrorEvent Error;
public Monitor()
{
watcher.Path = bookedPath;
watcher.Filter = "*.xls";
watcher.NotifyFilter = NotifyFilters.LastWrite;
watcher.Changed += new FileSystemEventHandler(watcher_Changed);
watcher.Error += new ErrorEventHandler(watcher_Error);
}
void watcher_Error(object sender, ErrorEventArgs e)
{
Error(e.GetException());
}
void watcher_Changed(object sender, FileSystemEventArgs e)
{
if (e.ChangeType != WatcherChangeTypes.Created) return;
FileDropped(e.FullPath);
}
public void Start()
{
watcher.EnableRaisingEvents = true;
}
public void Stop()
{
watcher.EnableRaisingEvents = false;
}
}
Simple form with Listbox:
public partial class Form1 : Form
{
Monitor monitor = new Monitor();
public Form1()
{
InitializeComponent();
FormClosing += new FormClosingEventHandler(Form1_FormClosing);
Load += new EventHandler(Form1_Load);
monitor.FileDropped += new Monitor.FileDroppedEvent(monitor_FileDropped);
monitor.Error += new Monitor.ErrorEvent(monitor_Error);
}
void Form1_Load(object sender, EventArgs e)
{
monitor.Start();
}
void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
monitor.Stop();
}
void monitor_Error(Exception ex)
{
listBox1.Items.Add(ex.Message);
}
void monitor_FileDropped(string FullPath)
{
listBox1.Items.Add(FullPath);
}
}
What am I doing wrong?

Try this out. Works for me for a very similar task.
watcher.NotifyFilter = NotifyFilters.FileName;
watcher.Created += new FileSystemEventHandler(handler);
watcher.Renamed += new RenamedEventHandler(handler);

This may be because the file metadata hasn't been updated yet. This may happen if you are continuously writing to the file.

Have you tried the following:
watcher.Path = directory name;
watcher.NotifyFilter = NotifyFilters.LastWrite;
watcher.Filter = "*.xls";
watcher.Changed += OnDirectoryChange;
watcher.Error += OnError;
watcher.EnableRaisingEvents = true;
// Watch only files not subdirectories.
watcher.IncludeSubdirectories = false;

Your issue is with the filters as well as your events I believe. NotifyFilters.LastAccess will only trigger when a file is opened. Try using:
NotifyFilters.LastWrite | NotifyFilters.CreationTime
This will watch for written/created files. Next, hook up to the Created delegate to handle newly created files:
watcher.Created += YourDelegateToHandleCreatedFiles
The way FileSystemWatcher works is to first use the NotifyFilters to limit the event triggers. Then, you use the actual events to do the work. By hooking into the Created event you'll only do work when a file is created.

FileSystemWatcher: multiple type

I want to send a file which has been found when the System Watcher has discoverd a created file ending with ".txt", ".doc" or ".docx". My Problem is that the System Watcher discover just files ending with ".txt".
Here is my Code:
private String Attachmenttosend
{
get { return attachmentfile; }
set { attachmentfile = value; }
}
private void NewFileSystemWatcher()
{
String filter = "*.txt,*.doc,*.docx";
string[] FileExtension = filter.Split(',');
for (int i = 0; i < FileExtension.GetLength(0); i++)
{
watcher = new FileSystemWatcher(folder); // on its own Thread
watcher.Created += new FileSystemEventHandler(NewEMail);
attachmenttosend.Add(Attachmenttosend);
watcher.Filter = FileExtension[i];
watcher.EnableRaisingEvents = true;
watchlist.Add(watcher);
}
Send(Attachmenttosend);
}
private void NewEMail(Object source, FileSystemEventArgs e)
{
while (Locked(e.FullPath)) // check if the file is used
{
Thread.Sleep(10);
}
Attachmenttosend = e.FullPath; // store the filename
}

I think this will help you,just create a console app on the fly and paste this in and try it out:
private static string[] filters = new string[] { ".txt", ".doc", ".docx" };
static void Main(string[] args)
{
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = #"C:\...\...\...";//your directory here
/* Watch for changes in LastAccess and LastWrite times, and
the renaming of files or directories. */
watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName | NotifyFilters.DirectoryName;
//dont set this
//watcher.Filter = "*.txt";
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.Deleted += new FileSystemEventHandler(OnChanged);
watcher.Renamed += new RenamedEventHandler(OnRenamed);
watcher.EnableRaisingEvents = true;
Console.ReadKey();
}
private static void OnChanged(object source, FileSystemEventArgs e)
{
if(filters.Contains(Path.GetExtension(e.FullPath)))
{
Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
//Attachmenttosend = e.FullPath;
}
}
private static void OnRenamed(object source, RenamedEventArgs e)
{
if (filters.Contains(Path.GetExtension(e.FullPath)))
Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
}
Also as Kunal pointed out
attachmenttosend.Add(Attachmenttosend);
I guess from the uppercase and lower case that you are trying to add to the backing field of the property its own property,dont,also...you dont add to a string only += (concat).
Unless attachmenttosend is a for example a list of strings.

Program exits when FileSystemWatcher.Changed event is raised (C#)

So, I'm trying to make a file changed notifier, and I need to make it so the text in a textbox updates whenever the contents of the file are changed. This is what I have so far:
string path = "C:/Users/Max/Dropbox/Public/IM.txt";
StringBuilder b = new StringBuilder();
private void Window_Loaded(object sender, EventArgs e)
{
TB.Text = File.ReadAllText(path);
b.Append(TB.Text);
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = path.Remove(path.Length - 6, 6);
watcher.NotifyFilter = NotifyFilters.LastWrite;
watcher.Filter = "*.txt";
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.EnableRaisingEvents = true;
TB.SelectionStart = TB.Text.Length;
TB.ScrollToCaret();
}
private void OnChanged(object source, FileSystemEventArgs e)
{
TB.Text = File.ReadAllText(path);
}
This seems to raise the event correctly, but as soon as it touches the code in the OnChanged event, the program exits, no errors or anything, just closes. I have tried to stop it from closing, I have even tried putting e.Cancel under the formclosing event, but nothing seems to work. Any ideas? I can provide more info if needed.

Have you tried wrapping the code in try catch
private void OnChanged(object source, FileSystemEventArgs e)
{
try
{
TB.Text = File.ReadAllText(path);
}catch(Exception e)
{
//Show exception in messagebox or log to file.
}
}

Try this in your Changed method
if (TB.InvokeRequired)
{
TB.Invoke(new MethodInvoker(delegate { TB.Text = File.ReadAllText(path); }));
}