How do I properly use a function in a do/while loop? - powershell

Question

I have created a function that creates a specific UI element with text input forms. This form also has three buttons:
One is supposed to display the text inputs again to do the same function again.
Another is supposed to finish and close the UI, passing the text input into the variables.
The last is supposed to cancel the UI element, doing nothing with anything in the text input forms.
Now I know the loop in the code isn't really complete, but I am having issues with it even performing the loop as well as passing the text forms into the variables. I know its something I am doing but it seems correct to me when I look at it.
Changed from an if loop, a while loop, and now a do/while loop.
Changed the position of the variables between the do section into the while section. Same for the if and while loops.
do {
ChangeDesc
}
while ($result -eq [System.Windows.Forms.DialogResult]::Retry)
{
$PC = Get-WmiObject -Class Win32_OperatingSystem -ComputerName $HNInputBox.Text
$PC.Description = $DescInputBox.Text
$PC.Put()
}
ChangeDesc is the name of the function and works just as intended.
Expected to work is to loop the function 'ChangeDesc', and then when the 'Retry' or 'Ok' button is pressed, pass those forms to the variables as shown.
Currently, it will display the form, and when the 'Retry' button is pressed, the forms are passed properly and then the UI is closed out, the 'Ok' button does not pass any input and the 'Cancel' does the same thing.
Below is the rest of my lines of code for clarification.
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
function ChangeDesc {
$form = New-Object System.Windows.Forms.Form
$form.Text = 'Data Entry Form'
$form.Size = New-Object System.Drawing.Size(300,210)
$form.StartPosition = 'CenterScreen'
$AnotherButton = New-Object System.Windows.Forms.Button
$AnotherButton.Location = New-Object System.Drawing.Point(15,130)
$AnotherButton.Size = New-Object System.Drawing.Size(75,23)
$AnotherButton.Text = 'Another?'
$AnotherButton.DialogResult = [System.Windows.Forms.DialogResult]::Retry
$form.AcceptButton = $AnotherButton
$form.Controls.Add($AnotherButton)
$FinishedButton = New-Object System.Windows.Forms.Button
$FinishedButton.Location = New-Object System.Drawing.Point(100,130)
$FinishedButton.Size = New-Object System.Drawing.Size(75,23)
$FinishedButton.Text = 'Finished'
$FinishedButton.DialogResult = [System.Windows.Forms.DialogResult]::OK
$form.CancelButton = $FinishedButton
$form.Controls.Add($FinishedButton)
$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Point(185,130)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Text = 'Cancel'
$CancelButton.DialogResult = [System.Windows.Forms.DialogResult]::Cancel
$form.CancelButton = $CancelButton
$form.Controls.Add($CancelButton)
$HNLabel = New-Object System.Windows.Forms.Label
$HNLabel.Location = New-Object System.Drawing.Point(10,20)
$HNLabel.Size = New-Object System.Drawing.Size(280,20)
$HNLabel.Text = 'Enter Host Name:'
$form.Controls.Add($HNLabel)
$HNInputBox = New-Object System.Windows.Forms.TextBox
$HNInputBox.Location = New-Object System.Drawing.Point(10,40)
$HNInputBox.Size = New-Object System.Drawing.Size(260,20)
$form.Controls.Add($HNInputBox)
$DescLabel = New-Object System.Windows.Forms.Label
$DescLabel.Location = New-Object System.Drawing.Point(10,70)
$DescLabel.Size = New-Object System.Drawing.Size(280,20)
$DescLabel.Text = 'Enter Description:'
$form.Controls.Add($DescLabel)
$DescInputBox = New-Object System.Windows.Forms.TextBox
$DescInputBox.Location = New-Object System.Drawing.Point(10,90)
$DescInputBox.Size = New-Object System.Drawing.Size(260,20)
$form.Controls.Add($DescInputBox)
$form.Topmost = $true
$form.Add_Shown({$HNInputBox.Select()})
$result = $form.ShowDialog()
}

Answer 1

Your form is already closed when the loop terminates, and the variables you're trying to use are local to your function. Assign the values you're trying to use to script- or global-scope variables at the end of the function, and the code should do what you expect:
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
function ChangeDesc {
$form = New-Object Windows.Forms.Form
...
$script:result = $form.ShowDialog()
$script:hostname = $HNInputBox.Text
$script:description = $DescInputBox.Text
}
do {
ChangeDesc
} while ($script:result -eq [Windows.Forms.DialogResult]::Retry)
$PC = Get-WmiObject Win32_OperatingSystem -Computer $script:hostname
$PC.Description = $script:description
$PC.Put()