How to stop PowerShell unrolling an array when called from another script

Question

I have a script that is running in PowerShell 7 (for better Unicode support) and I need to run a certain batch of commands in PowerShell 5 due to some DLL incompatibility. This means (afaik) I can't use dot sourcing.

PowerShell 7 calling code: `

$files = powershell.exe -ExecutionPolicy Bypass -File "$PSScriptRoot\FileInfo.ps1" -Path $FolderToProcess -Title $moduleTitle -GUID $guid

FileInfo.ps1 loops through a set of files and returns an array of PSCustomObject

$arr = @()

foreach ($file in $finalFiles)  {

    $item = [PSCustomObject]@{
        i = $file.i
        j = $file.j
        k = $file.k
    }

    $arr += $item
}

return $arr

However, what happens when I try to use the $files variable in the calling script, is that the result of the called script is actually an array of strings and is useless.

How do I either:

A) Tell the calling script that the result of the script should be an array; or

B) Have the 'sending' script not process the result as a string and pass back an array as expected?

score 3 · Accepted Answer · answered Nov 03 '22 at 06:52

You might serialize the object (array) in the callee and deserialize it in the caller.

(As an aside: try to avoid using the increase assignment operator (+=) to create a collection)

Callee (FileInfo.ps1)

$arr = foreach ($file in $finalFiles)  {
    [PSCustomObject]@{
        i = $file.i
        j = $file.j
        k = $file.k
    }
}
[System.Management.Automation.PSSerializer]::Serialize($Arr)

Caller (PowerShell 7 calling code)

$PSSerial = powershell.exe -ExecutionPolicy Bypass -File "$PSScriptRoot\FileInfo.ps1" -Path $FolderToProcess -Title $moduleTitle -GUID $guid
$Files = [System.Management.Automation.PSSerializer]::Deserialize($PSSerial)

How to stop PowerShell unrolling an array when called from another script

1 Answers1