Validate an arbitrary number of PowerShell script parameters

Question

It is possible in PowerShell to validate the parameters passed to a script and also enables auto completion, as seen below:

myscript.ps1:

param([Parameter(Mandatory=$false)][String][ValidateSet('abc',
                                                        'def',
                                                        'ghi')] $argument
     )

But this only enables the auto completion for the first argument. I want number of "auto complete"-able parameters to be arbitrary.

Therefore after typing:

PS C:\> .\myscript.ps1 def (additional white space at the end) and
pressing tab, I want the possible parameters to be auto completed again PS C:\> .\myscript.ps1 def abs

How do I code this in the param(...) part?

mklement0 · Accepted Answer · 2018-11-22 19:56:17Z

3

If you do want to pass values as individual arguments separated with whitespace, use the ValueFromRemainingArguments parameter attribute:

param(
  [Parameter(ValueFromRemainingArguments)]
  [ValidateSet('abc', 'def', 'ghi')]
  [string[]] $argument
 )

Note that $argument is now an array of values, in which PowerShell collects all positional arguments for you.

The potential down-side is that this subjects all positional arguments to the validation, so if you also need to pass other arguments, you'll have to prefix them with the parameter name (e.g., -foo bar).

Therefore, consider using a single, explicitly array-valued parameter instead:

param(
      [ValidateSet('abc', 'def', 'ghi')] 
      [string[]] $argument
     )

That way, $argument will receive multiple values if passed with , as the separator, and in addition to tab-completing the 1st value, each additional one after typing , can be tab-completed too.

./myscript a<tab>  # -> ./myscript abc

./myscript abc, d<tab<  # -> ./myscript abc, def

edited Nov 22, 2018 at 19:56

answered Nov 22, 2018 at 19:39

mklement0

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1 Comment

mklement0 Over a year ago

My pleasure, @user69453; glad to hear it helped.

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