Question

Bottom Line Up Front

I’m looking for a method to validate powershell (v1) command line parameters without propagating exceptions back to the command line.

Details

I have a powershell script that currently uses param in conjunction with [ValidateNotNullOrEmpty] to validate command line paramaters:

param(
   [string]
   [ValidateNotNullOrEmpty()]$domain = $(throw "Domain (-d) param required.")
)

We’re changing the paradigm of error handling where we no longer want to pass exceptions back to the command line, but rather provide custom error messages. Since the param block can not be wrapped in a try catch block, i’ve resorted to something like the following:

param(
   [string]$domain = $("")
)
Try{
   if($domain -like $("")){
      throw "Domain (-d) param required."
    }
...

}Catch{
#output error message 
}

My concern is that we’re bypassing all of the built-in validation that is available with using param. Is my new technique a reasonable solution? Is there a better way to validate command line params while encapsulating exceptions within the script? I’m very much interested in see how PowerShell professionals would handle this situation.

Any advice would be appreciated.

Answer 1

As I mentioned in a comment: more I read your description, more I come to the conclusion that you should not worry about “bypassing all built-in validation”. Why? Because that’s exactly your target. You want to bypass it’s default behavior, so if that’s what you need and have to do – than just do it. 😉