Dynamic Parameters - with Dynamic ValidateSet - powershell

Question

I have a script that I've been working on to provide parsing of SCCM log files. This script takes a computername and a location on disk to build a dynamic parameter list and then present it to the user to choose the log file they want to parse. Trouble is I cannot seem to get the ValidateSet portion of the dynamic parameter to provide values to the user. In addition the script won't display the -log dynamic parameter when attempting to call the function.
When you run it for the first time you are not presented with the dynamic parameter Log as I mentioned above. If you then use -log and then hit tab you’ll get the command completer for the files in the directory you are in. Not what you’d expect; you'd expect that it would present you the Logfile names that were gathered during the dynamic parameter execution.
PSVersion 5.1.14409.1012
So the question is how do I get PowerShell to present the proper Validate set items to the user?
If you issue one of the items in the error log you get the proper behavior:
Here are the two functions that i use to make this possible:
function Get-CCMLog
{
[CmdletBinding()]
param([Parameter(Mandatory=$true,Position=0)]$ComputerName = '$env:computername', [Parameter(Mandatory=$true,Position=1)]$path = 'c:\windows\ccm\logs')
DynamicParam
{
$ParameterName = 'Log'
if($path.ToCharArray() -contains ':')
{
$FilePath = "\\$ComputerName\$($path -replace ':','$')"
if(test-path $FilePath)
{
$logs = gci "$FilePath\*.log"
$LogNames = $logs.basename
$logAttribute = New-Object System.Management.Automation.ParameterAttribute
$logAttribute.Position = 2
$logAttribute.Mandatory = $true
$logAttribute.HelpMessage = 'Pick A log to parse'
$logCollection = New-Object System.Collections.ObjectModel.Collection[System.Attribute]
$logCollection.add($logAttribute)
$logValidateSet = New-Object System.Management.Automation.ValidateSetAttribute($LogNames)
$logCollection.add($logValidateSet)
$logParam = New-Object System.Management.Automation.RuntimeDefinedParameter($ParameterName,[string],$logCollection)
$logDictionary = New-Object System.Management.Automation.RuntimeDefinedParameterDictionary
$logDictionary.Add($ParameterName,$logParam)
return $logDictionary
}
}
}
begin {
# Bind the parameter to a friendly variable
$Log = $PsBoundParameters[$ParameterName]
}
process {
# Your code goes here
#dir -Path $Path
$sb2 = "$((Get-ChildItem function:get-cmlog).scriptblock)`r`n"
$sb1 = [scriptblock]::Create($sb2)
$results = Invoke-Command -ComputerName $ComputerName -ScriptBlock $sb1 -ArgumentList "$path\$log.log"
[PSCustomObject]#{"$($log)Log"=$results}
}
}
function Get-CMLog
{
param(
[Parameter(Mandatory=$true,
Position=0,
ValueFromPipelineByPropertyName=$true)]
[Alias("FullName")]
$Path,
$tail =10
)
PROCESS
{
if(($Path -isnot [array]) -and (test-path $Path -PathType Container) )
{
$Path = Get-ChildItem "$path\*.log"
}
foreach ($File in $Path)
{
if(!( test-path $file))
{
$Path +=(Get-ChildItem "$file*.log").fullname
}
$FileName = Split-Path -Path $File -Leaf
if($tail)
{
$lines = Get-Content -Path $File -tail $tail
}
else {
$lines = get-cotnet -path $file
}
ForEach($l in $lines ){
$l -match '\<\!\[LOG\[(?<Message>.*)?\]LOG\]\!\>\<time=\"(?<Time>.+)(?<TZAdjust>[+|-])(?<TZOffset>\d{2,3})\"\s+date=\"(?<Date>.+)?\"\s+component=\"(?<Component>.+)?\"\s+context="(?<Context>.*)?\"\s+type=\"(?<Type>\d)?\"\s+thread=\"(?<TID>\d+)?\"\s+file=\"(?<Reference>.+)?\"\>' | Out-Null
if($matches)
{
$UTCTime = [datetime]::ParseExact($("$($matches.date) $($matches.time)$($matches.TZAdjust)$($matches.TZOffset/60)"),"MM-dd-yyyy HH:mm:ss.fffz", $null, "AdjustToUniversal")
$LocalTime = [datetime]::ParseExact($("$($matches.date) $($matches.time)"),"MM-dd-yyyy HH:mm:ss.fff", $null)
}
[pscustomobject]#{
UTCTime = $UTCTime
LocalTime = $LocalTime
FileName = $FileName
Component = $matches.component
Context = $matches.context
Type = $matches.type
TID = $matches.TI
Reference = $matches.reference
Message = $matches.message
}
}
}
}
}

Answer 1

The problem is that you have all the dynamic logic inside scriptblock in the if statement, and it handles the parameter addition only if the path provided contains a semicolon (':').
You could change it to something like:
if($path.ToCharArray() -contains ':') {
$FilePath = "\\$ComputerName\$($path -replace ':','$')"
} else {
$FilePath = $path
}
and continue your code from there

Answer 2

PS 6 can do a dynamic [ValidateSet] with a class:
https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_functions_advanced_parameters?view=powershell-6#dynamic-validateset-values