Getting all Named Parameters from Powershell including empty and set ones

I found this most useful for PS4 (Windows 2012 R2) - it includes default values / optional parameters:

$cmdName = $MyInvocation.InvocationName
$paramList = (Get-Command -Name $cmdName).Parameters
foreach ( $key in $paramList.Keys ) {
    $value = (Get-Variable $key -ErrorAction SilentlyContinue).Value
    if ( $value -or $value -eq 0 ) {
        Write-Host "$key -> $value"
    }
}

Check this solution out. This uses the CmdletBinding() attribute, which provides some additional metadata through the use of the $PSCmdlet built-in variable. You can:

1. Dynamically retrieve the command's name, using $PSCmdlet
2. Get a list of the parameter for the command, using Get-Command
3. Examine the value of each parameter, using the Get-Variable cmdlet

Code:

function test {
    [CmdletBinding()]
    param (
          [string] $Bar = 'test'
        , [string] $Baz
        , [string] $Asdf
    )
    # Get the command name
    $CommandName = $PSCmdlet.MyInvocation.InvocationName;
    # Get the list of parameters for the command
    $ParameterList = (Get-Command -Name $CommandName).Parameters;

    # Grab each parameter value, using Get-Variable
    foreach ($Parameter in $ParameterList) {
        Get-Variable -Name $Parameter.Values.Name -ErrorAction SilentlyContinue;
        #Get-Variable -Name $ParameterList;
    }
}

test -asdf blah;

Output

The output from the command looks like this:

Name                           Value                                           
----                           -----                                           
Bar                            test                                            
Baz                                                                            
Asdf                           blah                                            

Hopefully, some may find this one-liner useful:

function test()
{
    Param(
        [string]$foo,
        [string]$bar,
        [string]$baz = "baz"
    )

    $MyInvocation.MyCommand.Parameters | Format-Table -AutoSize @{ Label = "Key"; Expression={$_.Key}; }, @{ Label = "Value"; Expression={(Get-Variable -Name $_.Key -EA SilentlyContinue).Value}; }
}
test -foo "foo!"

Result

Keys Value
---- -----
foo  foo! 
bar       
baz  baz  

To read the value dynamically use the get-variable function / cmdlet

write-host (get-variable "foo")

To print out all of the parameters do the following

foreach ($key in $MyInvocation.BoundParameters.keys)
{
    $value = (get-variable $key).Value 
    write-host "$key -> $value"
}