How can I cast as a user object in PowerShell? - powershell

Question

I've got the following code which connects to every computer on the domain and checks the members of the local administrators group:
Foreach ($Computer in Get-ADComputer -Filter *){
$Path = $Computer.Path
$Name = ([ADSI]"$Path").Name
Write-Host $Name
$members = [ADSI]"WinNT://$Name/Administrators"
$members = #($members.psbase.Invoke("Members"))
ForEach($member in $members){
Write-Host $member.GetType().InvokeMember("Name", 'GetProperty', $null, $member, $null)
Write-Host $member.GetType().InvokeMember("AdsPath", 'GetProperty', $null, $member, $null)
}
}
I'm trying to store the value of $member in a $User object of some sort, so I can actually reference the attributes without all the crazy invoker stuff.
E.g., in pseudocode I want:
$user = (User) $member;
Write-Host $user.Name
Write-Host $user.AdsPath
I'm new to PowerShell, however... and I'm not sure if I really understand how to cast to an object type within it.

Answer 1

You want to create a custom object (or PSObject) with the specified members and values:
Foreach ($Computer in Get-ADComputer -Filter *){
$Path=$Computer.Path
$Name=([ADSI]"$Path").Name
write-host $Name
$members =[ADSI]"WinNT://$Name/Administrators"
$members = #($members.psbase.Invoke("Members"))
ForEach($member in $members){
$propsWanted = #('Name' , 'AdsPath') # An array of the properties you want
$properties = #{} # This is an empty hashtable, or associative array, to hold the values
foreach($prop in $propsWanted) {
$properties[$prop] = $member.GetType().InvokeMember($prop, 'GetProperty', $null, $member, $null)
}
$user = New-Object PSObject -Property $properties
$user # This is an object representing the user
}
}
Just to go over some of the changes:
I'm putting all of the property names you want into an array $propsWanted, and then iterating over that to invoke and get each one. This lets you easily work with more properties later, by adding the property names in a single place.
The $properties hashtable will store a key/value pair, where the key is the property name, and the value is the property value.
Once the hashtable is filled, you can pass it to the -Property parameter of New-Object when creating a PSObject.
You should use your new object and have a look at by testing a few things:
Pipe it to the Format- cmdlets to see various views:
$user | Format-Table
$user | Format-List
Check the values of its properties directly:
$user.Name
$user.AdsPath
If you make an array of these objects, you can filter them for example:
$user | Where-Object { $_.Name -like '*Admin' }
Alternatives
You might try using CIM or WMI, which will actually be a little friendlier:
CIM
$group = Get-CimInstance -ClassName Win32_Group -Filter "Name = 'Administrators'"
Get-CimAssociatedInstance -InputObject $group -ResultClassName Win32_UserAccount |
select -ExpandProperty Caption
Get-CimAssociatedInstance -InputObject $group -ResultClassName Win32_Group |
select -ExpandProperty Caption
WMI
$query = "ASSOCIATORS OF {Win32_Group.Domain='$($env:COMPUTERNAME)',Name='Administrators'} WHERE ResultClass = Win32_UserAccount"
Get-WmiObject -Query $query | Select -ExpandProperty Caption
$query = "ASSOCIATORS OF {Win32_Group.Domain='$($env:COMPUTERNAME)',Name='Administrators'} WHERE ResultClass = Win32_Group"
Get-WmiObject -Query $query | Select -ExpandProperty Caption
.NET 3.5 Required for this method:
Add-Type -AssemblyName System.DirectoryServices.AccountManagement
$ctype = [System.DirectoryServices.AccountManagement.ContextType]::Machine
$context = New-Object -TypeName System.DirectoryServices.AccountManagement.PrincipalContext -ArgumentList $ctype, $env:COMPUTERNAME
$idtype = [System.DirectoryServices.AccountManagement.IdentityType]::SamAccountName
$group = [System.DirectoryServices.AccountManagement.GroupPrincipal]::FindByIdentity($context, $idtype, 'Administrators')
$group.Members |
select #{N='Domain'; E={$_.Context.Name}}, samaccountName
Attribution
All of the above alternatives were taken directly from this "Hey, Scripting Guy!" article, The Admin's First Steps: Local Group Membership. It goes into detail about all of these, including the [ADSI] method. Worth a read.
How to Actually Cast
I just realized I didn't actually answer this question, even though it's not exactly what you needed. Classes/types are specified with square brackets. In fact, when you did this:
[ADSI]"WinNT://$Name/Administrators"
You casted a [String] (the string literal in ") to an [ADSI] object, which worked because [ADSI] knows what to do with it.
Other examples:
[int]"5"
[System.Net.IPAddress]'8.8.8.8'
Since we don't know the type of the "user" object you're seeking (or it's not even really loaded), you can't use this method.