Working with ExtensionData attribute (byte arrays)

Question

Hello all,
I am working with the ExtensionData attribute in PowerShell, which is in byte array form. What I am wanting to do is change a part of this ExtensionData attribute, but still keep the byte array form. What I am currently trying makes the change successfully,
but I lose the byte array form. For example, before changing the ExtensionData attribute, Group1's ExtensionData attribute is populated on several lines within the attribute. After changing the attribute, Group1's ExtensionData attribute has all the same values,
but is now contained on a single line. Here is the code used:
#Finding Group1's ExtensionData attribute, in string form
$ExtensionData = Get-ADGroup "Group1" -Properties extensiondata | select -ExpandProperty extensiondata | ForEach-Object {
[System.Text.Encoding]::ASCII.GetString($_)
#Let's assume Group1's ExtensionData attribute looks like this (multiple lines):
#OldLine1
#OldLine2
#OldLine3
$StringOld = "OldLine1"
$StringNew = "NewLine1"
#making sure line I want to change is present in string form of ExtensionData attribute, then we change the part we want
If($ExtensionData -match $StringOld){
$ExtensionData -replace "$StringOld","$StringNew"
#Now we convert our new ExtensionData string form back to ASCII form
$change = [System.Text.Encoding]::ASCII
$NewExtensionData = $change.GetBytes($ExtensionData)
#Now, we can replace Group1's ExtensionData attribute with our new ExtensionData attribute
Set-ADGroup Group1 -Replace @{extensiondata=$NewExtensionData}
#However, now Group1's ExtensionData attribute looks like this (no multiple lines):
#NewLine1OldLine2OldLine3
How can I replace a line in the ExtensionData attribute and still keep the multiple lines within the attribute?

Answer 1

David,
Thanks again for taking time to help me out with this problem! I've solved my problem, but had to perform a few steps along the way. Long story short, I slightly modified the code you provided using -match and -replace for the strings, and then
when I tried to use -replace on the set-adgroup cmdlet, PowerShell griped and said value already present.
However, I was able to get it to work by clearing the extensiondata attribute first and then using -add. This put the bytes into the extensiondata attribute as expected, but there were 2 problems with this. First, it looked like each byte was it's own array
within the attribute. Second, the original ExtensionData attribute had strings in it, not bytes. I have since realized that bytes is how PowerShell reads the array, but not how ADUC displays it.
What I did was use the following code:
cls
$ExtensionData = @(
Get-ADGroup "Group1" -Properties extensiondata |
Select-Object -ExpandProperty extensiondata |
ForEach-Object {
[System.Text.Encoding]::ASCII.GetString($_)
$StringOld = "OldString"
$StringNew = "NewString"
for ($i = 0; $i -lt $ExtensionData.Count; $i++)
if ($ExtensionData[$i] -match $StringOld)
$ExtensionData[$i] = $ExtensionData[$i] -replace "$Stringold","$StringNew"
Set-ADGroup SmartDL-test -replace @{extensiondata=$ExtensionData}
As you can see, I still use -match and -replace to swap out the part of ExtensionData that I want. But it turns out I didn't need to convert the strings into bytes before using the set-adgroup command. I was able to just replace the part of the extensiondata
collection I wanted, and then just paste the entire new collection into the attribute, and for my purposes it appeared to work.
Anyway, I really appreciate your help on this, and it must be difficult helping someone troubleshoot when you can't see specifically what they're trying to do. Your post was extremely helpful however, and it led to the solution that worked for me. Thanks
again!