Question

I’m doing some scripting in PowerShell, and I was wondering if there’s a way to “declare” a parameter “X” the same way parameter “-Credential” is declared, for example in Get-WMIObject cmdlet.

Let me be more specific. The Credential parameter in almost all cmdlets is a PSCredential Object. But, the argument can be either a PSCredential Object or, a String Object with the username.

[CmdletBinding()]
param ([Parameter(Mandatory = $false)]
       [System.Management.Automation.PSCredential]
       $Credential)

The problem comes when passing a string. Of course, an argument transformation on the parameter cannot be done. Cannot convert the type “System.String” into a type PSCrendential.

Answer 1

Give this a try:

param(
    [System.Management.Automation.Credential()]
    $Credential=[System.Management.Automation.PSCredential]::Empty
)

As to parameter argument transformation, check this awesome script:

http://poshcode.org/3024