How to select multiple subobjects of an object in powershell - powershell

Question

The goal is to select all users from a list of groups which contains the subojects "Users" with X users. This user list should be written later as batch to an SQL Server. The goal ist to have a table with the user properties and the groupname + id.
To make the selection and mapping faster, i have tried to work with the select command of powershell. But there is a problem when more than one user is in the group
$GroupUsers = #()
foreach ($group in $groups) {
$GroupUsers = New-Object -TypeName PSObject -Property #{
UserLoginName = $group.Users.LoginName
UserTitle = $group.Users.Title
UserEmail = $group.Users.Email
GroupName = $group.Title
} | Select UserLoginName, UserTitle, UserEmail, GroupName
$GroupUsers+= $GroupUsers
}
The output which is generated looks like the following:
UserId : 33
UserLoginName : WalterX.test.com
UserTitle : Walter X
UserEmail : x#mail.de
GroupName : Group1
GroupId : 1
UserId : {1, 2, 3, 4...}
UserLoginName : {User1.test.com, User2.test.com,User3.test.com ...}
UserTitle : {User1,User2,User3...}
UserEmail : {User1#mail.com,User2#mail.com...}
GroupName : Group2
GroupId : 2
As you can see the first user is exported correctly. The second entry in the array has on the UserLoginName, Title and EMail property multiple users in it...

Answer 1

Don't use +=it's ineffective as it rebuilds the complete array on each addition
Assign the output of the foreach to a variable instead, using a [PSCustomObject]
nest another foreach to iterate the users of the group.
$GroupUsers = foreach($group in $groups) {
foreach($user in $group.Users){
[PSCustomObject]#{
UserLoginName = $User.LoginName
UserTitle = $User.Title
UserEmail = $User.Email
GroupName = $group.Title
}
}
}