How do I find a user by DisplayName in one CSV file given a DistinguishedName is another CSV file? - powershell

Question

I have two CSV files with tab-separated values.
CSV1:
GivenName Surname DisplayName Manager
John Smith John Smith Oliver Twist
CSV2:
SAMAccountName mail DistinguishedName
John Smith johns#example.com CN=John Smith,CN=Users,DC=example,DC=com
Oliver Twist olivert#example.com CN=Oliver Twist,CN=Users,DC=example,DC=com
What I've wanted to do is to compare the CSV1 with CSV2 and match the manager name in Manager column in CSV1 file with CSV2 DistinguishedName column value (i.e. "CN=Oliver Twist") as in this example and export to a new CSV file like this:
SAMAccountName mail Manager
John Smith johns#example.com Oliver Twist
There might be hundreds of distinguished names in CSV2 file as mentioned and all I want is output from comparing and matching the DistinguishedName column value "CN=whatever name " with the Manager column in CSV1.
Here is the script I tried:
$csv1 = Import-Csv -Path 'C:temp\AD.csv'
$csv2 = Import-Csv -Path 'C:\temp\AD_ExportDN.csv'
$csv3 = foreach ($record in $csv2) {
$matchingRecord = $csv1 | Where-Object { $_.manager -eq $record.manager }
# if your goal is to ONLY export records with a matching email address,
# uncomment the if ($matchingRecord) condition
#if ($matchingRecord) {
$record | Select-Object *, #{Name = 'manager'; Expression = {$matchingRecord.DistinguishedName}}
#}
}
$csv3 | Export-Csv -NoTypeInformation -Force -Path 'C:\temp\merged_for_AD2.csv'

Answer 1

Your question inspired me to add an new feature to the Join-Object script/Join-Object Module I am maintaining (see also: In Powershell, what's the best way to join two tables into one?).
The feature is explained in issue: #29 key expressions.
In your case the required command will be something like:
$Csv1 |Join $Csv2 -On Manager -Equals { [RegEx]::Match($_.DistinguishedName, '(?<=CN=).*(?=,CN=Users)') }
Which returns:
GivenName : John
Surname : Smith
DisplayName : John Smith
Manager : Oliver Twist
SAMAccountName : Oliver Twist
mail : olivert#example.com
DistinguishedName : CN=Oliver Twist,CN=Users,DC=example,DC=com
For the specific regular expression '(?<=CN=).*(?=,CN=Users)':
.* refers to any sequence of characters that is
Preceded by CN= ((?<=CN=), regex Lookbehind)
and followed by CN=Users ((?=,CN=Users), regex lookahead)