Working with hash of arrays

PowerShell Help
1

Hi,

I’m new to powershell, and having a bit of trouble with my first script. I’m pulling group memberships from AzureAD users (as a list of groups per each member) and wish to format as a list of members per each group. So my method was to create a hash of arrays, with groups as a key, and its members as an array value. Here’s what I have:

# list of users by userPrincipalName
$upns = @('moe@stooge.com', 'larry@stooge.com', 'curly@stooge.com')

$users = New-Object System.Collections.ArrayList
$groupMemberships = @{}

# Convert userPrincipalName to User Object
ForEach ($upn in $upns) {
if ( $user = Get-AzureADUser -Filter "userPrincipalName eq '$upn'" ) {
$users += $user
}
}

# Collect membership for each seen group
ForEach ( $user in $users ) {
ForEach ( $seenGroup in Get-AzureADUserMembership -All $true -ObjectID $user.ObjectId ) {
if ( $groupMemberships.ContainsKey( $seenGroup ) ) {
$groupMemberships[ $seenGroup ] += $user
} else {
$groupMemberships[ $seenGroup ] = @();
$groupMemberships[ $seenGroup ] += $user
}
}
}

My problem is in pushing users into the hash of arrays. If the hash key doesn’t exist, I create a new empty array as the hash value, then add the user to it. Problem is that all of the resulting hashes only contains a single user in the array - I’m not able to detect the resulting hash key “if ( $groupMemberships.ContainsKey( $seenGroup )”, so with each iteration (over groups), a new array is created, deleting the previous array.

I suspect I am having issues with scope, but not sure how to fix it.

 

Thanks for your help,

Rick

2

If the purpose of the script is to get “list of members per each group” you can use something like:

$UPNList = @(
    'moe@stooge.com'
    'larry@stooge.com'
    'curly@stooge.com'
)

$myOutput = foreach ($UPN in $UPNList) {
    if ($AzureADUser = Get-AzureADUser -Filter "UserPrincipalName eq '$UPN'") {
        if ($GroupList = Get-AzureADUserMembership -All $true -ObjectID $AzureADUser.ObjectId) {
            [PSCustomObject]@{
                UPN = $UPN
                GroupList = $GroupList.DisplayName
            }
        }
    }
}

$myOutput

I don’t think a hash table of arrays is the data structure you need here.
I recommend that you format your output as a PS Object as shown above.

3

Hi Sam,

Thanks for your reply, much appreciated. However I am looking for the opposite output:

group1  {user1, user...}

group... {user1, user...}

Which is what I meant by “list of users in each group”.

The hash structure is useful because the same directory can appear multiple times across the users. Placing each directory as a hash key naturally combines each unique directory data into a single instance (because keys have to be unique).

Why won’t my test for a key (my line 18) find an occurence generated (my line 22) in a previous loop?

Rick

4

Working script below. Returns a hash, with group display names as keys, and an array of group members (user principal names) as values.

$UPNList = @(
    'moe@stooge.com'
    'larry@stooge.com'
    'curly@stooge.com'
)

$users = New-Object System.Collections.ArrayList
$groupMemberships = @{}

# Convert userPrincipalName to User Object
ForEach ($UPN in $UPNList) {
    if ( $user = Get-AzureADUser -Filter "userPrincipalName eq '$UPN'" ) {
        $users += $user
    }
}

# Collect membership for each seen group
ForEach ( $user in $users ) {
    ForEach ( $seenGroup in Get-AzureADUserMembership -All $true -ObjectID $user.ObjectId ) {
        $displayName = $seenGroup.DisplayName
        $userPrincipalName = $user.UserPrincipalName
        if ( $groupMemberships[ $displayname ] ) {
            $groupMemberships[ $displayName ] += $userPrincipalName
        } else {
            $groupMemberships[ $displayName ] = @( $userPrincipalName )
        }
    }
}

$groupMemberships | Format-List
5 
$UPNList = @(
    'moe@stooge.com'
    'larry@stooge.com'
    'curly@stooge.com'
)

$UserGroupMembership = foreach ($UPN in $UPNList) {
    if ($AzADUser = Get-AzureADUser -Filter "UserPrincipalName eq '$UPN'") {
        if ($GroupList = Get-AzureADUserMembership -All $true -ObjectId $azAdUser.ObjectId) {
            [PSCustomObject]@{
                UPN       = $UPN
                GroupList = $GroupList.DisplayName
            }
        }
    }
}

$GroupUserMembership = foreach ($GroupName in ($UserGroupMembership.GroupList | select -Unique)) {
    [PSCustomObject]@{
        GroupName  = $GroupName
        MemberList = ($UserGroupMembership | where GroupList -Contains $GroupName).UPN
    }
}

$UserGroupMembership | FT -a 
$GroupUserMembership | FT -a
6

Hs Sam,

Very elegant. Looks like I should learn more about PSCustomObject and how it’s used in PowerShell scripting.

Thanks!

Rick