PowerShell Try/Catch with If Statements

Question

Problem/Details

I am working in PowerShell and trying to figure out how custom Try Catch statements work. My current major issue involves mixing Try/Catch and If statements. So the idea of what I am trying to achieve is something like this:

try {
 if (!$someVariable.Text) { throw new exception 0 }
 elseif ($someVariable.Text -lt 11) { throw new exception 1 }
 elseif (!($someVariable.Text -match '[a-zA-Z\s]')) { throw new exception 2}
}
catch 0 {
 [System.Windows.Forms.MessageBox]::Show("Custom Error Message 1")
}
catch 1 {
 [System.Windows.Forms.MessageBox]::Show("Custom Error Message 2")
}
catch 2 {
 [System.Windows.Forms.MessageBox]::Show("Custom Error Message 3")
}

Now I know the above code is very inaccurate in terms of what the actual code will be, but I wanted to visually display what I'm thinking and trying to achieve.

Question

Does anyone know how to create custom error messages with PowerShell that could assist me with achieving something close to the above idea and explain your answer a bit? Thank you in advance

So far, the link below is the closest thing I have found to what I'm trying to achieve:

PowerShell Try, Catch, custom terminating error message

Answer 1

The Error you throw is stored at $_.Exception.Message

$a = 1
try{
 If($a -eq 1){
 throw "1"
 }
}catch{
 if ($_.Exception.Message -eq 1){
 "Error 1"
 }else{
 $_.Exception.Message
 }
}

• Brandon: Ah! Thank you. I get it now. So I can simply use throw and append anything I want in " " and then when I do my catch statement... I can then parse through those with either an if or a switch. Perfect, perfect. Thank you. I don't know how I wasn't getting that.

Answer 2

I would suggest using the $PSCmdlet ThrowTerminatingError() method. Here's an example:

Function New-ErrorRecord
{
 param(
 [String]$Exception,
 [String]$ExceptionMessage,
 [System.Management.Automation.ErrorCategory] $ErrorCategory,
 [String] $TargetObject
 )
 $e = New-Object $Exception $ExceptionMessage
 $errorRecord = New-Object System.Management.Automation.ErrorRecord $e, $ErrorID, $ErrorCategory, $TargetObject
 return $ErrorRecord
}
Try
{
If (not condition)
{
 $Error = @{
 Exception = 'System.Management.Automation.ParameterBindingException'
 ExceptionMessage = 'Error text here'
 ErrorCategory = [System.Management.Automation.ErrorCategory]::InvalidArgument
 TargetObject = ''
 }
 $PSCmdlet.ThrowTerminatingError((New-ErrorRecord @Error))
}
} Catch [System.Management.Automation.ParameterBindingException]
{
 'do stuff'
}

• Brandon: I will file this away for a later use. But for now, the simple answer provided by @ArcSet has proven to be very helpful