Issue with using properties in an array and custom calculated property

So I have the following code that ingests AD users on a domain controller. The following throws an error:

# User Props to select
$user_props = @(
        'Name',
        'DistinguishedName',
        'SamAccountName',
        'Enabled',
        'SID'
        )

# Get AD groups an AD user is a member of
$user_groups = @{ label = 'GroupMemberships'; expression = { (Get-ADPrincipalGroupMembership -Identity $_.DistinguishedName).Name } }

# Get AD Users
$users = Get-ADUser -Filter * -Property $user_props | Select-Object $user_props, $user_groups -ErrorAction Stop -ErrorVariable _error

However, if I were to change $users to the following:

$users = Get-ADUser -Filter * -Property $user_props | Select-Object Name, DistinguishedName, SamAccountName, Enabled, SID, $user_groups -ErrorAction Stop -ErrorVariable _error

I no longer get this error. Is there a way I can define $user_props such that I don’t need to type out each property and still use my custom calculated property $user_groups?

I believe the issue has to do with mixing an array ($user_props) with a hashtable ($user_groups) but I’m unsure how to best write this. Thank you for the help!

>Solution :

The easiest way to "concatenate" two variables into one flat array is to use the @(...) array subexpression operator:

... |Select-Object @($user_props;$user_groups) ...