Unable to utilize ErrorMessage property with ValidateSet in Function - powershell

Question

I am currently practicing the use of functions in PowerShell and am running into an error. I created the function below to accept DC Super Hero names and return the name of the hero being passed to the function.
function Get-DCHero {
[CmdletBinding()]
param (
[Parameter(Mandatory)][ValidateSet('Batman','Superman','Aquaman','Wonder Woman','Flash',ErrorMessage = "'{0}' is not a DC Super Hero. Please trying one of the following: '{1}'")]
[string]$Name
)
Write-OutPut "$Name is a DC Super hero."
}
As of now the function works properly without the ErrorMessage portion on the ValidateSet. When including the ErrorMessage portion I am receiving the following error:
Get-DCHero -Name
Property 'ErrorMessage' cannot be found for type 'System.Management.Automation.CmdletBindingAttribute'.
At C:\Users\AAP8801\DCSuperHero.ps1:5 char:98
+ ... n','Flash', ErrorMessage = "'{0}' is not a DC Super Hero. Please tryi ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (ErrorMessage = ...llowing: '{1}'":NamedAttributeArgume
ntAst) [], RuntimeException
+ FullyQualifiedErrorId : PropertyNotFoundForType
When a parameter is passed to the function that is not part of the validation set I would like to able to edit the error message being throw. Can anyone tell me why I am unable to do this successfully?

Answer 1

To complement Santiago Squarzon's helpful answer by spelling out the [ValidateScript()] workaround he mentions, which is slightly easier than defining a custom attribute class:
function Get-DCHero {
[CmdletBinding()]
param (
[Parameter(Mandatory)]
[ValidateScript({
$set = 'Batman','Superman','Aquaman','Wonder Woman','Flash'
if ($_ -in $set) { return $true } # OK
throw "'$_' is not a DC superhero. Please try one of the following: '$($set -join ',')'"
})]
[string]$Name
)
"$Name is a DC superhero."
}

Answer 2

As Mathias explained in comments, the ErrorMessage property is available on the PowerShell SDK v6.2.0 and above.
As a workaround in Windows PowerShell, you could use the ValidateScript Attribute Declaration or you could create your own attribute declaration by inheriting from ValidateEnumeratedArgumentsAttribute, Base Type of the ValidateSet Class.
The following example can help you get started, and if you're interested in learning more, I would recommend you these nice articles from Kevin Marquette:
Powershell: Creating and using custom attributes
Powershell: Creating parameter validators and transforms
Class Definition
using namespace System.Management.Automation
class MyDCHeroSet : ValidateEnumeratedArgumentsAttribute {
[scriptblock] $Set
[string] $ErrorMessage
[void] ValidateElement([object] $Object) {
$ValidValues = & $this.Set
if($Object -notin $ValidValues) {
throw [ValidationMetadataException]::new(
[string]::Format(
$this.ErrorMessage,
$Object, ($ValidValues -join ',')
)
)
}
}
}
Implementation and Testing
function Get-DCHero {
[CmdletBinding()]
param (
[Parameter(Mandatory)]
[MyDCHeroSet(
Set = { 'Batman', 'Superman', 'Aquaman', 'Wonder Woman', 'Flash' },
ErrorMessage = "'{0}' is not a DC Super Hero. Please trying one of the following: '{1}'"
)]
[string] $Name
)
Write-Output "$Name is a DC Super hero."
}
Get-DCHero -Name Spiderman