How do I create an input box with a cancel button that will end a loop in my script?

Question

I have been working on a script for my client and I am having trouble getting it to work properly. I stole most of the code from the PowerShell Tip of the Week "Creating a Custom Input Box". I also took someone's code for the Show-MessageBox function.
I have slightly modified the original code with two parameters and an additional text box. The first field is for an e-mail address and the second is for an employee number.
I need to know how I can get a Do Until loop to recognize when the cancel button is pushed and break the loop and effectively end the script. The work happens at the end but perhaps I need something added/modified in the InputBox function.
I want the script to check to see if anything has been entered in the second text box. If empty it displays a message and calls the InputBox function again. Then if there is something I use elseif to check to see if it matches my RegEx (digits only). If
it doesn't match it will loop and call the InputBox function again.
This all works fine. The problem I am having is that I cannot cancel out of the form. I'd like the loop to continue until the second box matches my RegEx or Cancel is clicked. Clicking cancel doesn't break the loop. I need to know how I can stop the loop
when cancel is pressed. I've seen Stack "Overflow: PowerShell Cancel Button Stop Script" but I don't think this will work in a loop.
Any help would be awesome. As a note, I DO NOT want to use the VB Interaction stuff.
function InputBox {
param ($Name,$EN)
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
$objForm = New-Object System.Windows.Forms.Form
$objForm.Text = "Data Entry Form"
$objForm.Size = New-Object System.Drawing.Size(300,200)
$objForm.StartPosition = "CenterScreen"
$objForm.KeyPreview = $True
$objForm.Add_KeyDown({if ($_.KeyCode -eq "Enter")
{$x=$objTextBox.Text;$objForm.Close()}})
$objForm.Add_KeyDown({if ($_.KeyCode -eq "Escape")
{$objForm.Close()}})
$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(75,120)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Text = "OK"
$OKButton.Add_Click({$objForm.Close()})
$objForm.Controls.Add($OKButton)
$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Size(150,120)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Text = "Cancel"
$CancelButton.Add_Click({$objForm.Close()})
$objForm.Controls.Add($CancelButton)
$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,20)
$objLabel.Size = New-Object System.Drawing.Size(280,20)
$objLabel.Text = "Employee Email Address:"
$objForm.Controls.Add($objLabel)
$objTextBox = New-Object System.Windows.Forms.TextBox
$objTextBox.Location = New-Object System.Drawing.Size(10,40)
$objTextBox.Size = New-Object System.Drawing.Size(260,20)
if ($Name) {
$objTextBox.Text = $Name
else {
$objTextBox.Text = "@domain.com"
$objLabel2 = New-Object System.Windows.Forms.Label
$objLabel2.Location = New-Object System.Drawing.Size(10,70)
$objLabel2.Size = New-Object System.Drawing.Size(280,20)
$objLabel2.Text = "Employee Number:"
$objForm.Controls.Add($objLabel2)
$objTextBox2 = New-Object System.Windows.Forms.TextBox
$objTextBox2.Location = New-Object System.Drawing.Size(10,90)
$objTextBox2.Size = New-Object System.Drawing.Size(260,20)
$objForm.Controls.Add($objTextBox)
$objForm.Controls.Add($objTextBox2)
$objForm.Topmost = $True
$objForm.Add_Shown({$objForm.Activate()})
[void] $objForm.ShowDialog()
$Script:ButtonName = $objTextBox.Text
$script:ButtonEN =$objTextBox2.Text
$ButtonName; $ButtonEN
Function Show-MessageBox{
Param(
[Parameter(Mandatory=$True)][Alias('M')][String]$Msg,
[Parameter(Mandatory=$False)][Alias('T')][String]$Title = "",
[Parameter(Mandatory=$False)][Alias('OC')][Switch]$OkCancel,
[Parameter(Mandatory=$False)][Alias('OCI')][Switch]$AbortRetryIgnore,
[Parameter(Mandatory=$False)][Alias('YNC')][Switch]$YesNoCancel,
[Parameter(Mandatory=$False)][Alias('YN')][Switch]$YesNo,
[Parameter(Mandatory=$False)][Alias('RC')][Switch]$RetryCancel,
[Parameter(Mandatory=$False)][Alias('C')][Switch]$Critical,
[Parameter(Mandatory=$False)][Alias('Q')][Switch]$Question,
[Parameter(Mandatory=$False)][Alias('W')][Switch]$Warning,
[Parameter(Mandatory=$False)][Alias('I')][Switch]$Informational)
#Set Message Box Style
IF($OkCancel){$Type = 1}
Elseif($AbortRetryIgnore){$Type = 2}
Elseif($YesNoCancel){$Type = 3}
Elseif($YesNo){$Type = 4}
Elseif($RetryCancel){$Type = 5}
Else{$Type = 0}
#Set Message box Icon
If($Critical){$Icon = 16}
ElseIf($Question){$Icon = 32}
Elseif($Warning){$Icon = 48}
Elseif($Informational){$Icon = 64}
Else{$Icon = 0}
#Loads the WinForm Assembly, Out-Null hides the message while loading.
[System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") | Out-Null
#Display the message with input
$Answer = [System.Windows.Forms.MessageBox]::Show($MSG , $TITLE, $Type, $Icon)
#Return Answer
Return $Answer
$num = "^\d+$"
do {
if (!($ButtonEN)) {
Show-MessageBox -Msg "You must enter a numeric value for the employee number." -Title "Employee Number Missing" -Critical
InputBox -Name $ButtonName
elseif ($ButtonEN -notmatch $num) {
Show-MessageBox -Msg "The employee number must contain numbers only!" -Title "Non-numerical characters found" -Critical
InputBox -Name $ButtonName
until ( ($ButtonEN -match $num) -or (<this is where I want to be able to use the cancel button>)

Answer 1

Here is a simple validation method.
function New-InputBox{
param(
$EmailAddress='',
$EmployeeNumber=''
Add-Type -AssemblyName System.Windows.Forms
$Form=New-Object System.Windows.Forms.Form
$Form.Text='Data Entry Form'
$Form.Size='300,200'
$Form.StartPosition='CenterScreen'
$OKButton=New-Object System.Windows.Forms.Button
$OKButton.Location='75,120'
$OKButton.Size='75,23'
$OKButton.Text='OK'
$OKButton.DialogResult='Ok'
$OKButton.CausesValidation=$true
$Form.Controls.Add($OKButton)
$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Size(150,120)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Text ='Cancel'
$CancelButton.DialogResult='Cancel'
$CancelButton.CausesValidation=$false
$Form.Controls.Add($CancelButton)
$Label1=New-Object System.Windows.Forms.Label
$Label1.Location='10,20'
$Label1.Size='280,20'
$Label1.Text='Employee Email Address:'
$Form.Controls.Add($Label1)
$TextBox1=New-Object System.Windows.Forms.TextBox
$TextBox1.Location='10,40'
$TextBox1.Size='260,20'
$textbox1.Name='EmailAddress'
$textbox1.Text=$EmailAddress
$Form.Controls.Add($textbox1)
$Label2=New-Object System.Windows.Forms.Label
$Label2.Location='10,70'
$Label2.Size='280,20'
$Label2.Text='Employee Number:'
$Form.Controls.Add($Label2)
$TextBox2=New-Object System.Windows.Forms.TextBox
$TextBox2.Location='10,90'
$TextBox2.Size='260,20'
$TextBox2.Name='EmployeeNumber'
$TextBox2.Text=$EmployeeNumber
$Form.Controls.Add($TextBox2)
$Form.AcceptButton=$OKButton
$Form.CancelButton=$CancelButton
$Form.Topmost = $True
$form1_FormClosing=[System.Windows.Forms.FormClosingEventHandler]{
if($Form.DialogResult -eq 'OK'){
if($textbox1.Text -eq ''){
[void][System.Windows.Forms.MessageBox]::Show('please enter an email address','Validation Error')
$_.Cancel=$true
}else{
# Check empno is all digits
if("$($TextBox2.Text)" -notmatch '^\d+$'){
[void][System.Windows.Forms.MessageBox]::Show('please enter a number "999999"','Validation Error')
$_.Cancel=$true
$form.add_FormClosing($form1_FormClosing)
$Form.Add_Shown({$Form.Activate()})
if($Form.ShowDialog() -eq 'Ok'){
# return the form contents
$Form
if($f=New-InputBox -EmailAddress [email protected]){
'Email is:{0} for Employee:{1}' -f $f.Controls['EmailAddress'].Text,$f.Controls['EmployeeNumber'].Text
}else{
Write-Host 'From cancelled!' -ForegroundColor red
¯\_(ツ)_/¯