Need help trimming the memberOf property of the Get-ADGroup results

I am trying to get the CN and MemberOf attributes from Get-ADGroup and I am having an issue trimming the unneeded info from the MemberOf property.

The code I am working with that gives me the results is as follows:

 Get-ADGroup -searchbase "OU=TargetOU,....." -filter * -properties * | select CN, Memberof | Format-List

It gives me the following results:

CN       : GroupName
Memberof : {CN=CN1blah,OU=OUblah,OU=OUblah,OU=OUblah,OU=OUblah,DC=DCBlah,DC=DCBlah,DC=DCBlah,DC=DCBlah,DC=DCBlah,CN=CN2blah,OU=OUblah,OU=OUblah,OU=OUblah,OU=OUblah,DC=DCBlah,DC=DCBlah,DC=DCBlah,DC=DCBlah,DC=DCBlah,CN=CN3blah,OU=OUblah,OU=OUblah,OU=OUblah,OU=OUblah,DC=DCBlah,DC=DCBlah,DC=DCBlah,DC=DCBlah,DC=DCBlah}

What I am looking for is this:

CN       : GroupName
Memberof : CN1blah,CN2blah,CN3blah

So I am trying to Trim MemberOf result down until only the CN1blah,CN2blah,CN3blah is left

I tried adding a split and substring to the MemberOf (see code below)and it produces an error

 Get-ADGroup -searchbase "OU=TargetOU,....." -filter * -properties * | select CN, Memberof.split(',')[0].Substring(3) | Format-List

Error is as follows:

Method invocation failed because [System.Char] does not contain a method named 'Substring'.
At line:1 char:1
+ get-adgroup -searchbase "OU=OUblah,OU=OUblah,OU=OUblah,OU=OUblah ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : MethodNotFound

I figure its something simple I am missing or I am going about it the wrong way.

Can anyone help me figure out how to get the results I am looking for?

Solution

You'll need to use a calculated property for the memberOf property:

Get-ADGroup -SearchBase 'OU=TargetOU,.....' -Filter * -Properties cn, memberof |
    Select-Object CN, @{ N='MemberOf'; E= { $_.Memberof -replace '^CN=|(?<!\\),.+' }} |
    Format-List

The replacement pattern will remove CN= from the start of the string and then everything after the first , that is not preceded by \.

The current expression will also result in an array, if you want to convert that array into a string you should also combine it with a -join:

E={ $_.Memberof -replace '^CN=|(?<!\\),.+' -join ',' }