PowerShell - Using input from TextBox wont work? - powershell

Question

I'm trying to make a GUI for an easy tool I need to check if a specific certificate is included in the file and Output the current and next line. This already works.
If I set the variables $INT1 and $Serial1 manually within the code it also works as intended.
e.g. $INT1=31 and $Serial1="5AA61E07726DAC13".
I always get an Error that the variable is empty when inputing the same values into the GUI and clicking OK. What am I doing wrong?
The code:
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
$objForm = New-Object System.Windows.Forms.Form
$objForm.StartPosition = "CenterScreen"
$objForm.Size = New-Object System.Drawing.Size(400,250)
$objForm.Topmost = $True
#Label+Textbox first question
$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,30)
$objLabel.Size = New-Object System.Drawing.Size(800,20)
$objLabel.Text = "INT of certificate"
$objForm.Controls.Add($objLabel)
$objTextBox = New-Object System.Windows.Forms.TextBox
$objTextBox.Location = New-Object System.Drawing.Size(10,50)
$objTextBox.Size = New-Object System.Drawing.Size(200,20)
$objForm.Controls.Add($objTextBox)
#Label+Textbox second question
$objLabel2 = New-Object System.Windows.Forms.Label
$objLabel2.Location = New-Object System.Drawing.Size(10,130)
$objLabel2.Size = New-Object System.Drawing.Size(800,20)
$objLabel2.Text = "Serialnumber of the certificate"
$objForm.Controls.Add($objLabel2)
$objTextBox2 = New-Object System.Windows.Forms.TextBox
$objTextBox2.Location = New-Object System.Drawing.Size(10,150)
$objTextBox2.Size = New-Object System.Drawing.Size(200,20)
$objForm.Controls.Add($objTextBox2)
$INT1 = $objTextBox.Text;
$Serial1 = $objTextBox2.Text;
#OK Button
$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(100,175)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Text = "OK"
$OKButton.Name = "OK"
#$OKButton.DialogResult = "OK"
$OKButton.Add_Click({Invoke-WebRequest -Uri http://CENSORED.crl -OutFile crl.crl;
$test=certutil.exe -dump crl.crl |Out-String -stream | Select-String -pattern "$Serial1" -Context 0,1
[void] [Windows.Forms.MessageBox]::Show($test)})
$objForm.Controls.Add($OKButton)
[void] $objForm.ShowDialog()
Thank you!

Answer 1

Here's a rewrite of your code.
I'm assuming that you want variables $INT1 and $Serial1 to be available after the windows closes.
In that case, fill them inside the Click() scriptblock and refer to them using $script: scoping, otherwise they are just new variables local to the scriptblock.
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
# these variables need to visible inside the Click scriptblock of the button
# and be also available after the windows closes
$INT1 = $null
$Serial1 = $null
$objForm = New-Object System.Windows.Forms.Form
$objForm.StartPosition = "CenterScreen"
$objForm.Size = New-Object System.Drawing.Size(400,250)
$objForm.Topmost = $True
#Label+Textbox first question
$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,30)
$objLabel.Size = New-Object System.Drawing.Size(800,20)
$objLabel.Text = "INT of certificate"
$objForm.Controls.Add($objLabel)
$objTextBox = New-Object System.Windows.Forms.TextBox
$objTextBox.Location = New-Object System.Drawing.Size(10,50)
$objTextBox.Size = New-Object System.Drawing.Size(200,20)
$objForm.Controls.Add($objTextBox)
#Label+Textbox second question
$objLabel2 = New-Object System.Windows.Forms.Label
$objLabel2.Location = New-Object System.Drawing.Size(10,130)
$objLabel2.Size = New-Object System.Drawing.Size(800,20)
$objLabel2.Text = "Serialnumber of the certificate"
$objForm.Controls.Add($objLabel2)
$objTextBox2 = New-Object System.Windows.Forms.TextBox
$objTextBox2.Location = New-Object System.Drawing.Size(10,150)
$objTextBox2.Size = New-Object System.Drawing.Size(200,20)
$objForm.Controls.Add($objTextBox2)
#OK Button
$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(100,175)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Text = "OK"
$OKButton.Name = "OK"
#$OKButton.DialogResult = "OK"
$OKButton.Add_Click({
# you never seem to use variable $INT1, but if you do, refer to it as $script:INT1
# set the variables defined OUTSIDE the scriptblock using script-scoping
$script:INT1 = $objTextBox.Text
$script:Serial1 = $objTextBox2.Text
# create a full path and filename for the output of the Invoke-WebRequest call
$crlFile = Join-Path -Path ([System.IO.Path]::GetTempPath()) -ChildPath 'crl.crl'
Invoke-WebRequest -Uri 'http://CENSORED.crl' -OutFile $crlFile
$test = certutil.exe -dump $crlFile | Out-String -Stream | Select-String -Pattern $script:Serial1 -Context 0,1
[void] [Windows.Forms.MessageBox]::Show($test)
# delete the temporary file
$crlFile | Remove-Item -Force
})
$objForm.Controls.Add($OKButton)
[void] $objForm.ShowDialog()
# clean up the form from memory'
$objForm.Dispose()
# here you can again see what is inside variables $INT1 and $Serial1
Write-Host "Last entered values: $INT1 $Serial1"

Answer 2

All user interaction with your form happens in this, blocking call:
[void] $objForm.ShowDialog()
See the ShowDialog() method.
Therefore, if you want to store results from that user interaction in variables, place the assignments after the call, and reference the controls of interest.
# ... form setup
# Show the form modally (as a dialog).
# The call blocks until the form is closed.
# Note:
# You may want to examine the return value in case there
# are multiple ways to close your form, and one of those ways
# signals having *canceled*, for instance.
$null = $objForm.ShowDialog()
# Now you can get values from the controls and assign them to (script) variables.
$INT1 = $objTextBox.Text
$Serial1 = $objTextBox2.Text
Note: If you need to set script-level variables - i.e., variables visible after a .ShowDialog() call - from inside script blocks serving as event delegates (e.g., the script block passed to $OKButton.Add_Click()), you need to use the $script: scope, given that such script blocks run in a child scope too - see this answer.