FileSystemWatcher or something else?

[bminaeff]

I have a requirement for a project to take text files from a specific folder and load that data into a sql table then move that file to an archive folder. I do not know what the file name is going to be but I know the data inside will be in the format "Barcode|Carrier". The people delivering this file say they create it and move the file to my specific folder. However, I get an error saying that "The process cannot access the file 'Filename.txt' because it is being used by another process."

So I made some quick modifications to try to handle this but at seemingly random times the files are inserted into the folder and just sit there. Here is my code which has been modified alot in the field. Their files also had some lines (2-4) with no text so I added in that if statement. Also, I want to use the move method, but I was getting errors about the file being open so I write the file to my archive folder and delete the input file.

What can I do to get this to work? Should I just use a timer and poll the folder for new files? Thanks for the help. Also, cmd3 is my stored procedure and works fine.

 Private Sub FileSystemWatcher1_Changed(ByVal sender As System.Object, ByVal e As System.IO.FileSystemEventArgs) Handles FileSystemWatcher1.Created

        Dim mypath As String = My.Settings.OrderFilePath
        Dim archpath As String = My.Settings.ArchiveFilepath
        Dim filename As String = mypath & e.Name
        Try
            Dim myreader As New System.IO.StreamReader(filename)
            Dim location As Integer
            Dim barcode, carrier, myinput As String
            
            While myreader.EndOfStream = False
                myinput = myreader.ReadLine.ToString
                If myinput.Length > 1 Then
                    System.IO.File.WriteAllText(archpath & e.Name, myinput.ToString)
                    location = InStr(myinput, "|")
                    barcode = Mid(myinput, 1, location - 1)
                    carrier = Mid(myinput, location + 1)
                    cmd3.Parameters(0).Value = barcode
                    cmd3.Parameters(1).Value = carrier
                    cmd3.ExecuteNonQuery()
                Else
                    Exit While
                End If
            End While
            
            myreader.Close()
            System.IO.File.Delete(filename)
            'System.IO.File.Move(filename, archpath & e.Name)
            
        Catch ex As Exception
            If ex.Message = "The process cannot access the file '" & filename & "' because it is being used by another process." Then
                Call FileSystemWatcher1_Changed(sender, e)
            End If
            ' 
        End Try
    End Sub

 

[chiph]

The file system will make the file visible to you when it first gets started being written to. At that time, the other process has an exclusive lock on it, so you're not able to access it. Only when they're through writing to the file can you then read it.

A suggestion would be to have a FileSystemWatcher object tell you when the file has been closed. You should be able to set the NotifyFilter property to look for LastWrite.

Chip H.


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