Powershell TextBox automatically update file contents

Question

Anyone can help me fix my code below. I am displaying a log file in the textbox, but the textbox wont update automatically when the log file is updated. I tried using a timer but it wont work since it will refresh the whole form and the input file name will be reset too, so it will return a null value. Please go to "viewComo" function.

Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
[System.Windows.Forms.Application]::EnableVisualStyles()


#2. Instantiate a Form Object
#-----------------------------------------------------------------------------------------
$Form_MAIN = New-Object system.Windows.Forms.Form;
$Form_MAIN.ClientSize  = New-Object System.Drawing.Point(1024,1000);
$Form_MAIN.StartPosition = "manual";
$Form_MAIN.Location = New-Object System.Drawing.Size(600,300);
$Form_MAIN.BackColor = [System.Drawing.ColorTranslator]::FromHtml("#6699CC");
$Form_MAIN.text = "DataCenter Operation Applications";
$Form_MAIN.TopMost = $false;
$Form_MAIN.AutoSize = $false;
$Form_MAIN.AutoScale = $false;
$Form_MAIN.MaximizeBox = $false;

#3. Build the Form Components
#-----------------------------------------------------------------------------------------
$MainMenu = New-Object System.Windows.Forms.MenuStrip;

$Menu_File = New-Object System.Windows.Forms.ToolStripMenuItem("File");
$SubMenu_Open = New-Object System.Windows.Forms.ToolStripMenuItem("Open");
$SubMenu_Save = New-Object System.Windows.Forms.ToolStripMenuItem("Save");
$SubMenu_Exit = New-Object System.Windows.Forms.ToolStripMenuItem("Exit");

$Menu_DCApp = New-Object System.Windows.Forms.ToolStripMenuItem("DCApp");
$SubMenu_Reports_Checker = New-Object System.Windows.Forms.ToolStripMenuItem("Reports_Checker");
$SubMenu_Reports_Transfer = New-Object System.Windows.Forms.ToolStripMenuItem("Reports_Transfer");
$SubMenu_COB_Monitoring = New-Object System.Windows.Forms.ToolStripMenuItem("COB_Monitoring");
$SubMenu_AD_AccountLock_Checker = New-Object      System.Windows.Forms.ToolStripMenuItem("AD_AccountLock_Checker");

$Menu_Help = New-Object System.Windows.Forms.ToolStripMenuItem("Help");
$Menu_About = New-Object System.Windows.Forms.ToolStripMenuItem("About");

$GB_Top = New-Object system.Windows.Forms.Groupbox;
$GB_Top.height = 330;
$GB_Top.width = 990;
$GB_Top.text = "Como Checker, Please input the Service name below";
$GB_Top.location = New-Object System.Drawing.Point(15,30);
$GB_Top.Font = New-Object System.Drawing.Font('Calibri',12);


$TB_Top_Input = New-Object system.Windows.Forms.TextBox;
$TB_Top_Input.multiline = $true;
$TB_Top_Input.width = 840;
$TB_Top_Input.height = 30;
$TB_Top_Input.location = New-Object System.Drawing.Point(10,25);
$TB_Top_Input.Font = New-Object System.Drawing.Font('Calibri',10);


$TB_Top_Button = New-Object system.Windows.Forms.Button;
$TB_Top_Button.Text = "Search COMO";
$TB_Top_Button.width = 124;
$TB_Top_Button.height = 30;
$TB_Top_Button.location = New-Object System.Drawing.Point(850,25);
$TB_Top_Button.Add_Click({checkComoFiles})

$RB_LabelQuery = New-Object System.Windows.Forms.Label;
$RB_LabelQuery.Text = "Choose the Range to query:";
$RB_LabelQuery.AutoSize  = $true;
$RB_LabelQuery.width = 104;
$RB_LabelQuery.height = 10;
$RB_LabelQuery.location = New-Object System.Drawing.Point(10,55);
$RB_LabelQuery.Font = New-Object System.Drawing.Font('Callibri',9);

$RB_Option1 = New-Object system.Windows.Forms.RadioButton;
$RB_Option1.Text = "Last 1 Hour";
$RB_Option1.AutoSize  = $true;
$RB_Option1.width = 104;
$RB_Option1.height = 10;
$RB_Option1.location = New-Object System.Drawing.Point(170,55);
$RB_Option1.Font = New-Object System.Drawing.Font('Callibri',9);



$RB_Option2 = New-Object system.Windows.Forms.RadioButton;
$RB_Option2.Text = "Last 3 Hours";
$RB_Option2.AutoSize = $true;
$RB_Option2.width = 104;
$RB_Option2.height = 10;
$RB_Option2.location = New-Object System.Drawing.Point(270,55);
$RB_Option2.Font = New-Object System.Drawing.Font('Callibri',9);


$RB_Option3 = New-Object system.Windows.Forms.RadioButton;
$RB_Option3.Text = "Last 24 Hours";
$RB_Option3.AutoSize = $true;
$RB_Option3.width = 104;
$RB_Option3.height = 10;
$RB_Option3.location = New-Object System.Drawing.Point(360,55);
$RB_Option3.Font = New-Object System.Drawing.Font('Callibri',9);

$RB_LabelOutput = New-Object System.Windows.Forms.Label;
$RB_LabelOutput.Text = "Result:";
$RB_LabelOutput.AutoSize  = $true;
$RB_LabelOutput.width = 104;
$RB_LabelOutput.height = 10;
$RB_LabelOutput.location = New-Object System.Drawing.Point(10,85);
$RB_LabelOutput.Font = New-Object System.Drawing.Font('Calibri',12);


#$TB_Top_Output = New-Object system.Windows.Forms.TextBox;
#$TB_Top_Output.multiline = $true;
#$TB_Top_Output.width = 970;
#$TB_Top_Output.height = 200;
#$TB_Top_Output.location = New-Object System.Drawing.Point(10,110);

$dataGridView = New-Object System.Windows.Forms.DataGridView
$dataGridView.Size=New-Object System.Drawing.Size(970,200)
$dataGridView.Location = New-Object System.Drawing.Point(10,110); 
$dataGridView.BackgroundColor = "White";

#$form.Controls.Add($dataGridView)
$dataGridView.ColumnCount = 1
$dataGridView.ColumnHeadersVisible = $true
$dataGridView.Columns[0].Name = "Como Name"
$datagridview.Columns[0].Width = 300;
$datagridview.Font = New-Object System.Drawing.Font('Courier New',9);
$datagridview.Add_CellMouseDoubleClick({viewComoGrid})


$GB_Bottom = New-Object system.Windows.Forms.Groupbox;
$GB_Bottom.height = 600;
$GB_Bottom.width = 990;
$GB_Bottom.text = "View COMO";
$GB_Bottom.location = New-Object System.Drawing.Point(15,380);
$GB_Bottom.Font = New-Object System.Drawing.Font('Calibri',12);


$TB_Bottom_Input = New-Object system.Windows.Forms.TextBox;
$TB_Bottom_Input.multiline = $true;
$TB_Bottom_Input.width = 840;
$TB_Bottom_Input.height = 30;
$TB_Bottom_Input.location = New-Object System.Drawing.Point(10,20);
$TB_Bottom_Input.Font = New-Object System.Drawing.Font('Calibri',10);


$TB_Bottom_Button = New-Object system.Windows.Forms.Button;
$TB_Bottom_Button.Text = "View COMO";
$TB_Bottom_Button.width = 124;
$TB_Bottom_Button.height = 30;
$TB_Bottom_Button.location = New-Object System.Drawing.Point(850,20);
$TB_Bottom_Button.Font = New-Object System.Drawing.Font('Calibri',10);
$TB_Bottom_Button.Add_Click({viewComo})

$RB_LabelOutput_Bottom = New-Object System.Windows.Forms.Label;
$RB_LabelOutput_Bottom.Text = "Result:";
$RB_LabelOutput_Bottom.AutoSize  = $true;
$RB_LabelOutput_Bottom.width = 104;
$RB_LabelOutput_Bottom.height = 10;
$RB_LabelOutput_Bottom.location = New-Object System.Drawing.Point(10,55);
$RB_LabelOutput_Bottom.Font = New-Object System.Drawing.Font('Calibri',12);


$TB_Top_Output_Bottom = New-Object system.Windows.Forms.TextBox;
$TB_Top_Output_Bottom.multiline = $true;
$TB_Top_Output_Bottom.size = New-Object System.Drawing.Size(970,510) 
$TB_Top_Output_Bottom.ReadOnly = $True
#$TB_Top_Output_Bottom.width = 970;
#$TB_Top_Output_Bottom.height = 510;
$TB_Top_Output_Bottom.location = New-Object System.Drawing.Size(10,80);
$TB_Top_Output_Bottom.ScrollBars = 'Both'
$TB_Top_Output_Bottom.Font = New-Object System.Drawing.Font('Courier New',9);


#4. Add the Components to the Group Boxes
#-----------------------------------------------------------------------------------------
$GB_Top.controls.AddRange(@($RB_LabelQuery, $RB_Option1,$RB_Option2,$RB_Option3,$TB_Top_Input,     $TB_Top_Button, $RB_LabelOutput, $dataGridView));
$GB_Bottom.controls.AddRange(@($L_Bottom_Output,$B_Enter, $TB_Bottom_Input, $TB_Bottom_Button,   $RB_LabelOutput_Bottom, $TB_Top_Output_Bottom  ));


#4. Add the Components to the Form
#-----------------------------------------------------------------------------------------
$Menu_File.DropDownItems.Add($SubMenu_Open);
$Menu_File.DropDownItems.Add($SubMenu_Save);
$Menu_File.DropDownItems.Add($SubMenu_Exit);

$Menu_DCApp.DropDownItems.Add($SubMenu_Reports_Checker);
$Menu_DCApp.DropDownItems.Add($SubMenu_Reports_Transfer);
$Menu_DCApp.DropDownItems.Add($SubMenu_COB_Monitoring);
$Menu_DCApp.DropDownItems.Add($SubMenu_AD_AccountLock_Checker);

$MainMenu.Items.Add($Menu_File);
$MainMenu.Items.Add($Menu_DCApp);  
$MainMenu.Items.Add($Menu_Help);
$MainMenu.Items.Add($Menu_About);

$Form_MAIN.controls.AddRange(@($MainMenu,$TB_Output));

#4.1 Add the Group Boxes to the Form
#-----------------------------------------------------------------------------------------
$Form_MAIN.controls.AddRange(@($GB_Top,$GB_Bottom));


#5. Code the Event Handlers
#-----------------------------------------------------------------------------------------
$SubMenu_Open.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Open File."; })
$SubMenu_Save.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Save File."; })
$SubMenu_Exit.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Exit Program."; })

$SubMenu_Reports_Checker.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Reports_Checker"; })
$SubMenu_Reports_Transfer.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Reports_Transfer"; })
$SubMenu_COB_Monitoring.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  COB_Monitoring"; })
$SubMenu_AD_AccountLock_Checker.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  AD_AccountLock_Checker"; })

$Menu_DCApp.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Options!"; })
$Menu_Help.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  Help me!"; })
$Menu_About.Add_Click({ $TB_Top_Output_Bottom.Text = "`r`n  All about ME."; })

function checkComoFiles {

$servicename= $TB_Top_Input.Text
$dataGridView.Rows.Clear()
$TB_Top_Input.Clear()

if ($RB_Option1.Checked) {
  $hours = 1

$ResultQuery = Get-ChildItem -Path C:\Users\user\Downloads\ -File | Where-Object {($_.LastWriteTime - gt (Get-Date (Get-Date).AddHours(-$hours))) } |
ForEach-Object { $_ | Select-String -List -Pattern $servicename  -SimpleMatch  |
        Select-Object -first 1 -ExpandProperty FileName}

 }


if ($RB_Option2.Checked) {
 $hours = 3

$ResultQuery = Get-ChildItem -Path C:\Users\user\Downloads\ -File | Where-Object {($_.LastWriteTime -gt (Get-Date (Get-Date).AddHours(-$hours))) } |
ForEach-Object { $_ | Select-String -List -Pattern $servicename  -SimpleMatch  |
        Select-Object -first 1 -ExpandProperty FileName}

}


if ($RB_Option3.Checked) {
 $hours = 24

$ResultQuery = Get-ChildItem -Path C:\Users\user\Downloads\ -File | Where-Object {($_.LastWriteTime -gt (Get-Date (Get-Date).AddHours(-$hours))) } |
ForEach-Object { $_ | Select-String -List -Pattern $servicename  -SimpleMatch  |
        Select-Object -first 1 -ExpandProperty FileName}

}

$dataGridView.Columns[0].Name = $servicename

$rows = @($ResultQuery)
foreach ($row in $rows)
{    
$dataGridView.Rows.Add($row)
}


}


Function viewComo { 

$comoName = $TB_Bottom_Input.Text
$openComolive = Get-Content C:\Users\user\Downloads\$comoName  
$TB_Top_Output_Bottom.Lines = $openComolive
$TB_Bottom_Input.Clear()

}

Function viewComoGrid {

$rowIndex = $datagridview.CurrentRow.Index
$columnIndex = $datagridview.CurrentCell.ColumnIndex

#Write-Host $rowIndex
#Write-Host $columnIndex 
#Write-Host $datagridview.Rows[$rowIndex].Cells[0].value
#Write-Host $datagridview.Rows[$rowIndex].Cells[$columnIndex].value

$comoNameGrid = $datagridview.Rows[$rowIndex].Cells[0].value
$openComoliveGrid = Get-Content C:\Users\user\Downloads\$comoNameGrid  

  $TB_Top_Output_Bottom.Lines = $openComoliveGrid
  $TB_Bottom_Input.Clear()

  }
#6. Display Form
#-----------------------------------------------------------------------------------------
$Form_Main.ShowDialog();

Im trying to use below timer in my above code but it wont work since the whole form will be refresh

$timer = new-object Windows.Forms.Timer
$timer.Interval=10000
$timer.add_Tick({$TB_Top_Output_Bottom.Lines = Get-Content C:\Users\user\Downloads\$logname | Out-String;     $TB_Top_Output_Bottom.Refresh()})
$timer.Start()

Answer 1

Original Version:

This isn't exactly intended to be an answer!
I think mklement0's answer is probably a safer way of getting the job done. But I remember reading about FileSystemWatcher some years ago, and having never used it before, wanted to give it a try.

Found this C# FileSystemWatcher answer, and figured out how to recreate the work in PowerShell.

Found this interesting use of SynchronizingObject for System.Timers.Timer that appears to allow Timer's Elapsed event to to run in the same thread as a control or form, and discovered that FileSystemWatcher also has a SynchronizingObject Property.

This seems to work flawlessly when editing and saving MyLogFile.TXT with NotePad.exe, but when I load MyLogFile.TXT in VSCode, the script either crashes or stops working. I think VSCode is locking the file and preventing the script from reading it, but I'm not really sure.

I would like to stress that this is an experiment, and this is outside my experience, use with with caution.

Basic code for setting up a Form for testing FileSystemWatcher:

using namespace System.Windows.Forms
Add-Type -AssemblyName System.Windows.Forms
[Application]::EnableVisualStyles()

$FilePathToWatch = $PSScriptRoot
$FileNameToWatch = "MyLogFile.TXT"
$FilePathNameToWatch = Join-Path -Path $FilePathToWatch -ChildPath $FileNameToWatch

$Form_MAIN = [Form]@{
    AutoSize = $false
    AutoScale = $false
    BackColor = '0x6699CC'
    ClientSize  = "1024,1000"
    Location = "600,300"
    MaximizeBox = $false
    StartPosition = "manual"
    Text            = "DataCenter Operation Applications"
    Topmost         = $true
}

$TextBox_Output = [TextBox]@{
    Anchor = 'Top, Left, Bottom, Right'
    Location = '12, 12'
    Multiline = $true
    Name = 'TextBox_Output'
    Size = "$($Form_MAIN.ClientSize.Width - 24), $($Form_MAIN.ClientSize.Height - 24)"
    Text = Get-Content -Raw $FilePathNameToWatch
}
$Form_Main.Controls.Add($TextBox_Output)

Code for setting up FileSystemWatcher, ending with ShowDialog() to open the form, $watcher.Dispose() to, as mklement0 pointed out, to stop $watcher from continuing to fire after form closes.:

[IO.FileSystemWatcher]$watcher = [IO.FileSystemWatcher]@{
    Path = $FilePathToWatch
    NotifyFilter = [IO.NotifyFilters]::LastWrite
    Filter = $FileNameToWatch
    SynchronizingObject = $TextBox_Output
}
$watcher.Add_Changed({
    $TextBox_Output.Text = Get-Content -Raw $FilePathNameToWatch
})
$watcher.EnableRaisingEvents = $true

$null = $Form_Main.ShowDialog()
$watcher.Dispose()

UPDATED Version:

Walk through of changes from above code, full code listed in order in following sections:

Add function GetLogFileContent for safely reading the file, or returning an empty string when the file doesn't exist.

using namespace System.Windows.Forms
Add-Type -AssemblyName System.Windows.Forms
[Application]::EnableVisualStyles()

$FilePathToWatch = $PSScriptRoot
$FileNameToWatch = "MyLogFile.TXT"
$FilePathNameToWatch = Join-Path -Path $FilePathToWatch -ChildPath $FileNameToWatch

function GetLogFileContent {
    param ( [Parameter(Mandatory = $true, Position = 0)][string]$FilePathName )
    if(Test-Path -PathType Leaf -LiteralPath $FilePathName) { Get-Content -Raw $FilePathName } else { '' }
}

Added code for Form's FormClosing event to shutdown $watcher so it no longer is firing events and properly disposed.

$Form_MAIN = [Form]@{
    AutoSize = $false
    AutoScale = $false
    BackColor = '0x6699CC'
    ClientSize  = "1024,1000"
    Location = "600,300"
    MaximizeBox = $false
    StartPosition = "manual"
    Text            = "DataCenter Operation Applications"
    Topmost         = $true
}
$Form_MAIN.Add_FormClosing({
    $watcher.Dispose()
})

The TextBox Text property is assigned results of call to GetLogFileContent function.

$TextBox_Output = [TextBox]@{
    Anchor = 'Top, Left, Bottom, Right'
    Location = '12, 12'
    Multiline = $true
    Name = 'TextBox_Output'
    Size = "$($Form_MAIN.ClientSize.Width - 24), $($Form_MAIN.ClientSize.Height - 24)"
    Text = GetLogFileContent $FilePathNameToWatch
}
$Form_Main.Controls.Add($TextBox_Output)

$watcher's NotifyFilter property now set for checking for both FileName and LastWrite. Just a reminder, SynchronizingObject set to the TextBox so it can be updated on the same thread.

[IO.FileSystemWatcher]$watcher = [IO.FileSystemWatcher]@{
    Path = $FilePathToWatch
    NotifyFilter = [IO.NotifyFilters]::FileName -bor [IO.NotifyFilters]::LastWrite
    Filter = $FileNameToWatch
    SynchronizingObject = $TextBox_Output
}

Added Deleted and Renamed events to $watcher to catch deletions and renames, and using GetLogFileContent function to populate the textbox Text property.

$watcher.Add_Changed({
    $TextBox_Output.Text = GetLogFileContent $FilePathNameToWatch
})
$watcher.Add_Deleted({
    $TextBox_Output.Text = ''
})
$watcher.Add_Renamed({
    $TextBox_Output.Text = if($_.Name -eq $FileNameToWatch) { GetLogFileContent $FilePathNameToWatch } else { '' }
})

Watcher.Dispose() removed from end of code (taken care of in FormClosing event).

$watcher.EnableRaisingEvents = $true
$null = $Form_Main.ShowDialog()

Answer 2

Note:

• This answer addresses the question as asked.

• Darin's helpful answer shows an alternative approach that doesn't unconditionally, periodically re-read the log file (based on a timer), but uses an event-based file-system watcher to only update re-read the file if and when it changes.

  • This is more elegant and generally preferable, except if the log file is updated very frequently, in which case you'd need a throttling mechanism (which the timer-based approach implicitly provides, though one could be implemented with the file-watcher approach too).

---

There is no obvious problem with your approach:

• The System.Windows.Forms.Timer type fires its events on the GUI thread and therefore allows modifying the form state.

• While script blocks ({ ... }) that are passed as event delegates in .add_<eventName>() calls run in a child scope of the script, thanks to PowerShell's dynamic scoping you can still read the variables from the script scope.

• Since WinForms is in control of the event loop when you show a form modally with .ShowDialog(), it is sufficient to assign new content to the .Lines property of your text-box control: the control should refresh automatically (and even an explicit .Refresh() call should not make the whole form refresh).

The following is a self-contained proof of concept:

• A background job is started that writes the current timestamp to a given file every second.

• The WinForms code uses a timer event to read that file and update its multi-line text box control with it.

using namespace System.Windows.Forms
using namespace System.Drawing

Add-Type -AssemblyName System.Windows.Forms

# Create the form.
$form = [Form] @{
  Text = "Textbox Timer-Based Refresh Demo"
  Size = [Size]::new(380,200)
  StartPosition = "CenterScreen"
}

# Create the textbox and add it to the form.
$form.Controls.AddRange(@(
  ($textBox = [TextBox] @{
    Location = [Point]::new(10, 10)
    Size = [Size]::new(320, 90)
    MultiLine = $true
  })
))

# Create a timer that fires every second, and
# reads the then-current file content.
$timer = [Timer]::new()
$timer.InterVal = 1000
$timer.add_Tick({
  $textBox.Lines = Get-Content -Raw $logName
})
$timer.Start()

# The log file to read.
$logName = 't.txt'

# Create a background job that updates the log file every second.
$jb = Start-Job {
  while ($true) {
    Get-Date > "$using:PWD/$using:logName"
    Start-Sleep 1
  }
}

# Show the form modally.
$null = $form.ShowDialog()

# Clean up
$timer.Dispose()
$jb | Remove-Job -Force