Receive-Job Powershell - powershell

Question

I'm trying to learn about how to properly use Receive-Job. My objective is to essentially have a job start and run something like this:
$Alldatasets = [PSCustomobject]#{}
$Alldatasets = if(Test-Path "Alldatasets"){
Get-ChildItemContent "Alldatasets" | ForEach {$_.Content | Add-Member #{Name = $_.Name} -PassThru} | Where Location -EQ $Location | Where {$Dataset.Count -eq 0 -or (Compare-Object $Dataset $_.Name -IncludeEqual -ExcludeDifferent | Measure).Count -gt 0}
}
$Alldatasets
Then return the output $Alldatasets back to the main script, which you can't see, but would be a table of custom objects.
I understand the process of receive-job, but nothing really tutorial-wise how to use it to return the custom object-table that I am making in the above example. Using wait-job | receive-job I get just the actual process details when I use Get-Member- $Alldatasets doesn't seem to be anywhere, but running the .ps1 script I wrote it in- It posts $Alldatasets. I just can't get $Alldatasets from receive-job.

Answer 1

You have to use Start-Job to be able to use 'Receive-Job`. And if you are going to use variables in it, you have to pass it as arguments because you are essentially spinning up a new process/thread and it will not have access to your local variables. Hence the param block.
$ScriptBlock = {
param(
[Parameter (Mandatory=$true,
Position = 0)]
$Location,
[Parameter (Mandatory=$true,
Position = 1)]
$DataSet
)
$Alldatasets = [PSCustomobject]#{}
$Alldatasets = if(Test-Path "Alldatasets"){
Get-ChildItemContent "Alldatasets" | ForEach {$_.Content | Add-Member #{Name = $_.Name} -PassThru} | Where Location -EQ $Location |
Where {$Dataset.Count -eq 0 -or (Compare-Object $Dataset $_.Name -IncludeEqual -ExcludeDifferent | Measure).Count -gt 0}}
Return $Alldatasets
}
Start-Job -ScriptBlock $ScriptBlock -ArgumentList $Location, $DataSet -Name "MyCustomJob"
$Alldatasets = Get-Job -Name "MyCustomJob" | Wait-Job | Receive-Job

Answer 2

I figured it out. It wasn't an issue of passing the object. It was an issue of directory.
It doesn't tell you in any of the tutorials I have found, so I will state it here.
Start-Job does not specify a location when starting. My above script performed Test-Path command with the assumption it was started in the original working directory. I had to specify a working directory in order for script to work:
$ScriptBlock = {
param(
[Parameter (Mandatory=$true,
Position = 0)]
$Location,
[Parameter (Mandatory=$true,
Position = 1)]
$WorkingDir,
[Parameter (Mandatory=$true,
Position = 3)]
$DataSet
)
Set-Location "$WorkingDir"
$Alldatasets = [PSCustomobject]#{}
$Alldatasets = if(Test-Path "Alldatasets"){
Get-ChildItemContent "Alldatasets" | ForEach {$_.Content | Add-Member #{Name = $_.Name} -PassThru} | Where Location -EQ $Location |
Where {$Dataset.Count -eq 0 -or (Compare-Object $Dataset $_.Name -IncludeEqual -ExcludeDifferent | Measure).Count -gt 0}}
Return $Alldatasets
}
Start-Job -ScriptBlock $ScriptBlock -ArgumentList $Location, $DataSet, $WorkingDir -Name "MyCustomJob"
$Alldatasets = Get-Job -Name "MyCustomJob" | Wait-Job | Receive-Job