PowerShell method Contains not working as expected - powershell

Question

I am very new to PowerShell and I need to prepare some PowerShell commands to a assign users some roles in Exchange Online. I first need to check if the user is assigned the role already and if not, I'll assign the role. But I just can't figure out how to check if one email address is part of list of email addresses.
I found many discussions on -contains or .Contains method not working but their solutions never worked for me. My code is below.
$L1Group = Get-MsolGroup | Where-Object { $_.DisplayName -eq "TEST_GROUP"}
$L1Members = Get-MsolGroupMember -GroupObjectId $L1Group.ObjectId
$CurrentMembers = Get-RoleGroupMember "Recipient Management" |
Select -Property WindowsLiveID
foreach ($user in $L1Members) {
if (!$CurrentMembers.Contains($user.EmailAddress)) {
Add-RoleGroupMember "Recipient Management" -Member $user.EmailAddress
}
}
It works fine without the if statement and it assigns roles as expected, but I need to skip users who are already members of the role group. I just cant figure out how to make the if statement work. If I use echo $CurrentMembers it returns list of 4 email addresses, just as expected and even if I try
$CurrentMembers -contains 'MyEmail#MyDomain.com'
it always returns False but the address is in the list.

Answer 1

Your code doesn't work the way you expect because this statement
$CurrentMembers = Get-RoleGroupMember "Recipient Management" |
Select -Property WindowsLiveID
produces a list of custom objects with a single property WindowsLiveID, but your check expects a list of strings. Expand the property to get that list of strings:
$CurrentMembers = Get-RoleGroupMember "Recipient Management" |
Select -Expand WindowsLiveID

Answer 2

This is a common question. .contains and -contains are different. $CurrentMembers may contain sub-properties.
PS C:\Users\admin\foo> 'hi there'.contains('hi')
True
PS C:\Users\admin\foo> 'hi','there' -contains 'hi'
True
Does this work? Another common question is how to get just the value from the property.
if (! ($CurrentMembers.windowsliveid -Contains $user.EmailAddress) )
Hmm, interesting how .contains() works with arrays. It's more like -contains. More confusion!
PS C:\Users\js\foo> $a = 'one','two','three'
PS C:\Users\js\foo> $a.contains('one')
True
PS C:\Users\js\foo> $a.contains('o')
False
PS C:\Users\js\foo> $a.contains
OverloadDefinitions
-------------------
bool IList.Contains(System.Object value)

Answer 3

Solution is in comments - "Select -Property WindowsLiveID -> Select -Expand WindowsLiveID"
– Ansgar Wiechers 2 hours ago
Hopefully Angsar will post an answer so he can get credit...
Here's a link to the M$oft doc for the Select-Object cmdlet:
https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/select-object?view=powershell-6