powershell Loop on scriptblocks

Question

I'm trying to export several information from a collection of objects into CSV files.

For this purpose I always have the following pipe :

 $users | < my filters/grouping/selects and expands> | Export-CSV ...

Instead of copy/paste these lines I would prefer to have an hashtable with as a key the CSV filename and and as a value the part between < ... >

So I did this :

$scriptblocks = @{"NonCompliantMail"={ ? {-not ([bool]($_.mail -as [Net.Mail.MailAddress])) } };
              "NonCompliantSAM"= { ? { ($_.samaccountname.Trim().Length - $_.samaccountname.Length) -ne 0 }};
              "MissingSN" = { ? {[string]::IsNullOrWhiteSpace($_.sn) } };
              "MissingGivenName" = { ? {[string]::IsNullOrWhiteSpace($_.givenname) } };
              "TrimSN" = { ? { (-not ([string]::IsNullOrWhiteSpace($_.sn))) -and (($_.sn.Trim().Length - $_.sn.Length) -ne 0) } };
              "TrimGivenName" = { ? { (-not ([string]::IsNullOrWhiteSpace($_.givenname))) -and (($_.givenname.Trim().Length - $_.givenname.Length) -ne 0) } }
              "MultipleEmails" = { group-object mail |? { $_.Count -gt 1 } | select -ExpandProperty Group | select mail,samaccountname }
              }

and I'm trying to execute it like that but it doesn't work :

$scriptblocks.getEnumerator() |% { $users | & $_.Value | Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ($_.Key + ".csv")) } 

Any ideas on how to do it ?

Regards. JB

Answer 1

Ok, so a Switch is a loop that tests each record of an array against a set of filters. If the record passes the filter it it run against the following scriptblock. The filters can be a literal match, a RegEx match, or a scriptblock similar to a Where statement. For your needs we'll be using the last of those. Check out this example and see if it accomplishes what you are going for:

Switch($users){
    {-not ([bool]($_.mail -as [Net.Mail.MailAddress])) }{$_|Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ("NonCompliantMail" + ".csv")) -append}
    {($_.samaccountname.Trim().Length - $_.samaccountname.Length) -ne 0 }{$_|Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ("NonCompliantSAM" + ".csv")) -append}
    {[string]::IsNullOrWhiteSpace($_.sn) }{$_|Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ("MissingSN" + ".csv")) -append}
    {[string]::IsNullOrWhiteSpace($_.givenname) }{$_|Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ("MissingGivenName" + ".csv")) -append}
    {(-not ([string]::IsNullOrWhiteSpace($_.sn))) -and (($_.sn.Trim().Length - $_.sn.Length) -ne 0) }{$_|Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ("TrimSN" + ".csv")) -append}
    {(-not ([string]::IsNullOrWhiteSpace($_.givenname))) -and (($_.givenname.Trim().Length - $_.givenname.Length) -ne 0) }{$_|Export-Csv -NoTypeInformation -Force -Encoding $encoding -Delimiter $delimiter -Path (Join-Path $scriptpath ("TrimGivenName" + ".csv")) -append}
}

That will run each user through the switch, and if it matches any of the conditions it will append it to the associated CSV file.

Edit: Ok, you didn't like Switch. If you really want to be able to execute scriptblocks in a ForEach-Object loop like that you can add parameters to your scriptblocks to allow piped data, but this doesn't completely solve your issue. I'll get to that in a moment. First, let's take your Group-Object mail option and set it up to accept input:

"MultipleEmails" = { group-object mail |? { $_.Count -eq 1 } | select -ExpandProperty Group | select mail,samaccountname }

becomes

"MultipleEmails" = {Param([Parameter(ValueFromPipeline=$True)][Object[]]$Users);$Users| group-object mail |? { $_.Count -eq 1 } | select -ExpandProperty Group | select mail,samaccountname }

I added Param([Parameter(ValueFromPipeline=$True)][Object[]]$Users);$Users| to the beginning of the scriptblock to do this. You can add that to the beginning of each scriptblock and they should all run similarly.

Then we have to force $users to be passed to it as an array by wrapping it as such: (,$users)
That allows this:

(,$users)|& $scriptblocks["multipleemails"]

That provides the output that you would expect it to. All that's left is to put that in your ForEach for $ScriptBlocks, along with keeping track of your current scriptblock:

$scriptblocks.keys|%{$sb=$_;(,$users)|& $scriptblocks["$sb"]}

That outputs everything from all of the scriptblocks. The only issue you now have is that you have no way to specify what CSV to output to. But this at least answers your original question.

Answer 2

The problem with this approach is that it is inefficient: you have to loop through all your $users once for each output file.

Another approach would be to use a switch statement to get around this (psuedocode to follow):

$file1 = "NonCompliantMail.csv"
$file2 = "NonCompliantSAM.csv"
$file3 = "MissingSN.csv"
$file4 = "MissingGivenName.csv"
$file5 = "TrimSN.csv"
$file6 = "TrimGivenName.csv"
$file7 = "UsersWhoDontMatchAnything.csv"

function WriteUserDataToFile
{

    param
    (
        $User,
        $OutFile
    )

    "Process the $User object to append to $OutFile"
}

switch ($users) 
{ 
    ("User matching criteria 1") {WriteUserDataToFile $_ $file1}
    ("User matching criteria 2") {WriteUserDataToFile $_ $file2} 
    ("User matching criteria 3") {WriteUserDataToFile $_ $file3} 
    ("User matching criteria 4") {WriteUserDataToFile $_ $file4} 
    ("User matching criteria 5") {WriteUserDataToFile $_ $file5}
    ("User matching criteria 6") {WriteUserDataToFile $_ $file6}
    default {WriteUserDataToFile $_ $file7}
}

So the users are matched against your criteria one-by-one and when a match is made the function to append that user's data to the file for that type of match is called.

Hope that is a fitting suggestion.