Use PowerShell to wrap an existing COM object

Question

Using PowerShell and System.DirectoryServices, I\'ve been given an object that looks like this:

   TypeName: System.__ComObject

Name                    


        

Answer 1

PowerShell reflection doesn't properly "see" these objects' properties and methods. To get to the properties and methods, I use some wrapper functions. Here is an example:

function Get-Property {
  param(
    [__ComObject] $object,
    [String] $propertyName
  )
  $object.GetType().InvokeMember($propertyName,"GetProperty",$NULL,$object,$NULL)
}

function Set-Property {
  param(
    [__ComObject] $object,
    [String] $propertyName,
    $propertyValue
  )
  [Void] $object.GetType().InvokeMember($propertyName,"SetProperty",$NULL,$object,$propertyValue)
}

function Invoke-Method {
  param(
    [__ComObject] $object,
    [String] $methodName,
    $methodParameters
  )
  $output = $object.GetType().InvokeMember($methodName,"InvokeMethod",$NULL,$object,$methodParameters)
  if ( $output ) { $output }
}

$ADS_ESCAPEDMODE_ON = 2      # see ADS_ESCAPE_MODE_ENUM
$ADS_SETTYPE_DN = 4          # see ADS_SETTYPE_ENUM
$ADS_FORMAT_X500_PARENT = 8  # see ADS_FORMAT_ENUM

$Pathname = New-Object -ComObject "Pathname"
# store initial EscapedMode
$escapedMode = Get-Property $PathName "EscapedMode"
# Enable all escaping
Set-Property $PathName "EscapedMode" @($ADS_ESCAPEDMODE_ON)
Invoke-Method $Pathname "Set" @("CN=Ken Dyer,OU=H/R,DC=fabrikam,DC=com",$ADS_SETTYPE_DN)
Invoke-Method $Pathname "Retrieve" @($ADS_FORMAT_X500_PARENT)
# outputs 'OU=H\/R,DC=fabrikam,DC=com'
$escapedMode = Set-Property $PathName "EscapedMode" @($escapedMode)
# set EscapedMode property back to initial value

Note that the Set-Property and Invoke-Method use an array as their final parameter, so I use @( ) when calling those functions.

Answer 2

Just a little different approach then Bill Stewart’s:

The idea is that usually you do not need/want to create multiple instances of the ComObject:

Function Invoke-ComObject([Parameter(Mandatory = $true)]$ComObject, [Switch]$Method, [Parameter(Mandatory = $true)][String]$Property, $Value) {
    If ($ComObject -IsNot "__ComObject") {
        If (!$ComInvoke) {$Global:ComInvoke = @{}}
        If (!$ComInvoke.$ComObject) {$ComInvoke.$ComObject = New-Object -ComObject $ComObject}
        $ComObject = $ComInvoke.$ComObject
    }
    If ($Method) {$Invoke = "InvokeMethod"} ElseIf ($MyInvocation.BoundParameters.ContainsKey("Value")) {$Invoke = "SetProperty"} Else {$Invoke = "GetProperty"}
    [__ComObject].InvokeMember($Property, $Invoke, $Null, $ComObject, $Value)
}; Set-Alias ComInvoke Invoke-ComObject

If it concerns a method, you need to add the –Method switch, in the case of a property, the cmdlet will automatically determine whether the property need to be get or set depending on whether a value is supplied. With this cmdlet you do not require the to create the ComObject first and retrieve e.g. to get the ComputerName (DN) from ADSystemInfo in a simple oneliner:

ComInvoke ADSystemInfo ComputerName

To do a the same with the PathName:

$EscapedMode = ComInvoke PathName EscapedMode
ComInvoke PathName EscapedMode @($ADS_ESCAPEDMODE_ON)
ComInvoke Pathname -Method Set @("CN=Ken Dyer,OU=H/R,DC=fabrikam,DC=com", $ADS_SETTYPE_DN)
ComInvoke Pathname -Method Retrieve @($ADS_FORMAT_X500_PARENT)
ComInvoke PathName EscapedMode @($EscapedMode)

A name NameTranslate example:

ComInvoke -Method NameTranslate Init @(1, "domain.com")
ComInvoke -Method NameTranslate Set @(8, "User001")
ComInvoke -Method NameTranslate Get @(1)

Or if you do want to have multiple instances you can first create the ComObject instance and then supply it to the ComInvoke function:

$NameTranslate = New-Object -ComObject NameTranslate
ComInvoke -Method $NameTranslate Init @(1, "domain.com")
ComInvoke -Method $NameTranslate Set @(8, "User001")
ComInvoke -Method $NameTranslate Get @(1)

_{For the latest Invoke-ComObject version, see: https://powersnippets.com/invoke-comobject/}