Making variables visible inside Powershell workflow - powershell

Question

I have five variables defined before a workflow that need to be available to the workflow, but I can't find out how to do it.
Putting the variables inside the workflow makes them visible, but that causes an issue with the CSV import that means extra properties are added to the object relating to the workflow that I don't want.
Code as follows:
$source = 'C:\Users\Koozer\a place\'
$rotateParams = 90, 90, 270
$cropParams = #(64, 64), (32, 0)
$images = Import-Csv "${source}images.csv"
$colNames = $images[0].psobject.properties.Name
Workflow StitchCropWorkflow {
foreach -parallel ($imageSet in $images) {
$magickRotParams = ''
$n = 0
foreach ($image in $colNames) {
$magickRotParams += '`( '''+$source+$imageSet.($image)+''' -rotate '+$rotateParams[$n]+' `) '
$n++
}
$finfo = [io.fileinfo]$imagePathSets[0]
$command = 'magick '+$magickRotParams+' +append -crop '+$cropParams[0][0]+'x'+$cropParams[0][1]+'+'+$cropParams[1][0]+'+'+$cropParams[1][1]+' +repage '''+$finfo.DirectoryName+'\'+$finfo.BaseName+'_stitch_crop'+$finfo.Extension+''''
echo $command
Invoke-Expression $command
}
}
StitchCropWorkflow

Answer 1

You can pass parameters to a workflow like you would do it for a function:
$source = 'C:\Users\Koozer\a place\'
$rotateParams = 90, 90, 270
$cropParams = #(64, 64), (32, 0)
$images = Import-Csv "${source}images.csv"
$colNames = $images[0].psobject.properties.Name
Workflow StitchCropWorkflow {
param (
$source,
$rotateParams,
$cropParams,
$images,
$colNames
)
# your code here
}
StitchCropWorkflow $source $rotateParams $cropParams $images $colNames

Answer 2

If you define a variable in a script containing a workflow, to access the variable within the workflow the syntax is $using:variable
As an example, here is a powershell script containing a workflow with a single param.
param([string]$ComputerName)
$VerbosePreference = "Continue"
workflow Start-Reboot {
param($server)
Write-Verbose "Input server is $server"
InlineScript{
New-Item -Path C:\Scripts\Logging\Start-Reboot-Single.log -ItemType File -ErrorAction SilentlyContinue | Out-Null
}
Sequence{
InlineScript
{
Try
{
Get-WmiObject -ComputerName $using:server -Class Win32_Service -Filter "Name='HealthService'" | Invoke-WmiMethod -Name PauseService | Out-Null
$operatingSystem = Get-WmiObject Win32_OperatingSystem -ComputerName $using:server -ErrorAction stop
$LastReboot = [Management.ManagementDateTimeConverter]::ToDateTime($operatingSystem.LastBootUpTime).ToString().Trim()
Write-Verbose "Last reboot time for $using:server is $LastReboot"
Write-Verbose "Here we restart $using:server, for testing no reboot is done"
Restart-Computer -ComputerName $using:server -Wait -For Wmi -Force
$OSRecheck = Get-WmiObject Win32_OperatingSystem -ComputerName $using:server -ErrorAction stop
$CurrentReboot = [Management.ManagementDateTimeConverter]::ToDateTime($OSRecheck.LastBootUpTime).ToString().Trim()
$props = [Ordered]#{
Server=$using:server
LastReboot=$LastReboot
CurrentReboot=$CurrentReboot
}
} Catch {
Write-Verbose "Oh no, problem with $using:server"
$rnd = Get-Random -Minimum 1 -Maximum 5
Start-Sleep -Seconds $rnd
$err = $_.Exception.GetType().FullName
$props = [Ordered]#{
Server=$using:server
LastReboot=$err
CurrentReboot=$null
}
} Finally {
$object = New-Object -TypeName PSObject -Property $props
$random = Get-Random -Minimum 2 -Maximum 15
Start-Sleep -Seconds $random
Write-Output $object | Out-File -Append -FilePath C:\Scripts\Logging\Start-Reboot-Single.log
}
}#inline end
}#sequence end
}#end workflow block
Start-Reboot -server $ComputerName