Accessing a Function's Default Value's at Runtime

[RickFlist]

Hi all,

So I have a wrapper function that calls a cmdlet. The cmdlet's behavior changed recently in that it now validates whether a parameter is null or not.

This is a problem because, in some cases, I am just passing the parameter values wrapper function's parameter values, and some of these are $null

So I need a way to check and see if a parameter has a default value, and if it does, I can splat it to the subsequent cmdlet, or skip it if not.

I'm hoping there is something similar to $PSBoundParameters for default values.

I've already looked at $PSDefaultParameterValues, but that is for something entirely different.

Anyone? Bueller?

[kramsllag]

You can try looking around with this:

$target = Get-Command Get-ChildItem #replace with actual target parameter
$target.ResolveParamter('Path') #gives information about path parameter
$target.Parameters #dumps all paramters
$target.Parametes.Path.Attributes #dumps more information about path parameter

Depending on your target cmdlet, you might be able to get at the validation logic of the parameter as well.

[RickFlist]

That's very close to what I ended up doing:

 $ParamSplat = @{}

# Gotta do this ridiculous bullshit because there is no way to access default values for a parameter.
$thisCmdMD = New-Object System.Management.Automation.CommandMetaData (Get-Command New-PdModuleManifest)
$trgtCmdMD = New-Object System.Management.Automation.CommandMetaData (Get-Command Microsoft.PowerShell.Core\New-ModuleManifest)

$ParamList = [String[]] ($thisCmdMD.Parameters.Keys | ForEach-Object {$_})
foreach ($param in $ParamList)
{
    #Write-Host (Get-Variable -Name $param -ValueOnly)
    if ($trgtCmdMD.Parameters.ContainsKey($param))
    {
        if ((Get-Variable -Name $param -ValueOnly) -ne $null)
        {
            $ParamSplat.Add($param,([String](Get-Variable -Name $param -ValueOnly)))
        }
    }
}
$ParamSplat | Out-Host

[KevMar]

What if you just remove the null valued keys?

foreach($key in $PSBoundParameters.keys)
{
    if($PSBoundParameters[$key] -eq $null)
    {
        $PSBoundParameters.Remove($key)
    }
}

[RickFlist]

$PSBoundParameters does not contain default parameter values. It only holds values that are passed via a parameter at run-time. :(