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The answer from @mklement0 is very helpful. https://stackoverflow.com/a/42699260/447901

I wanted to write a script that will produce all Github configuration settings. The PowerShellForGitHub module function Get-GitHubConfiguration only reports one at a time and you must already know the name of the setting. The settings supported vary across versions. This code gets the setting names based on the ValidateSet() for the $Name parameter and produces them all.

The question is... Is it important to test that the Attribute is of type [System.Management.Automation.ValidateSetAttribute]? What other type might it be?

Both of the $Names = lines produce the same array.

[CmdletBinding()]
#$Names = (Get-Command -Name 'Get-GitHubConfiguration').Parameters.Name.Attributes.ValidValues
$Names = ((Get-Command -Name 'Get-GitHubConfiguration').Parameters.Name.Attributes |
    Where-Object { $_ -is [System.Management.Automation.ValidateSetAttribute] }).ValidValues

foreach ($Name in $Names) {
    [PSCustomObject]@{
        Name = $Name
        Value = Get-GitHubConfiguration -Name $Name
    }
}
lit
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1 Answers1

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Assuming you're using this Get-GitHubConfiguration implementation, it is the -Name parameter you're interested in, and the following command extracts the values defined for its [ValidateSet] attribute:

$names = 
  (Get-Command Get-GitHubConfiguration).
    Parameters['Name'].
    Attributes.Where({ $_ -is [ValidateSet] }).
    ValidValues

$names then contains an array of strings (@('ApiHostName', 'ApplicationInsightsKey', ...))

PowerShell offers several attributes for validating arguments passed to parameters, but only the following allow discovery of a discrete set or a range of permissible values:

  • [ValidateSet], both with statically enumerated values, as in the case at hand, and - in PowerShell (Core) 7+ only - via a helper class that implements the IValidateSetValuesGenerator interface for dynamic generation of the permissible values.

  • [ValidateRange] for limiting arguments to a range of values, defined via inclusive endpoints.

mklement0
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  • @lit, it is _technically possible_ to combine them, but it _doesn't make sense_, given that _both_ constraints are enforced: if the `[ValidateSet]` values are a _subset_ of the values in the `[ValidateRange]` range, the latter has no effect. If the `[ValidateSet]` comprises values that are _outside_ the range specified `[ValidateRange]`, they can never be passed. – mklement0 Jan 05 '23 at 23:54