empty string error when binding parameters - indirect splatting - powershell

Question

I trying to run the this job with paramaters
$courses = {
param($securitytoken_path_a1 ,$EmailPasswordPath_a1 ,$EmailTo_a1)
Write-Host $securitytoken_path_a1 | Format-Table -Property *
C:\Users\so\Desktop\CanvasColleagueIntergration\PowerShells\DownloadInformation.ps1 -securitytoken_path ($securitytoken_path_a1) -emailPasswordPath $EmailPasswordPath_a1 -object "courses" -EmailTo $EmailTo_a1 -test $false
}
I am passing these parameters
$args1 = #{ "securitytoken_path_a1" = "C:\Credentials\CANVAS_API_PROD_FRANCO.TXT" ; "EmailPasswordPath_a1" = "C:\Credentials\EMAILFRANCO.txt"; "EmailTo_a1" = 'fpettigrosso#holyfamily.edu'}
when I invoke the job with this command it fails
Start-Job -ScriptBlock $courses -Name "Test" -ArgumentList $args1
when I try to see what is the issue I get the error back
Cannot bind argument to parameter 'emailPasswordPath' because it is an empty string.
+ CategoryInfo : InvalidData: (:) [DownloadInformation.ps1], ParameterBindingValidationException
+ FullyQualifiedErrorId : ParameterArgumentValidationErrorEmptyStringNotAllowed,DownloadInformation.ps1
+ PSComputerName : localhost
help

Answer 1

What you're looking for is splatting: the ability to pass a set of parameter values via a hashtable (or, less commonl, via an array) to a command.
Generally, in order to signal the intent to splat, a special sigil - # is required, so as to distinguish it from a single argument that just happens to be a hashtable:
$args1 passes a single argument that happens to be a hashtable.
#args1 - note how sigil $ has been replaced with # - tells PowerShell to apply splatting, i.e., to consider the hashtable's key-value pairs to be parameter-name-value pairs (note that the hashtable keys mustn't start with -, which is implied)
However, splatting only works directly for a given command, and you cannot relay a splatted hashtable via a command's single parameter.
That is, attempting to use -ArgumentList #args1 actually fails.
Your own solution works around that by passing the hashtable as-is to the script block and then explicitly accessing that hashtable's entries one by one.
An alternative solution is to use the hashtable argument to apply splatting inside the script block:
$courses = {
param([hashtable] $htArgs) # pass the hashtable - to be splatted later - as-is
$script = 'C:\Users\fpettigrosso\Desktop\CanvasColleagueIntergration\PowerShells\DownloadInformation.ps1'
& $script #htArgs # use $htArgs for splatting
}
Note, however, that the target command's parameter names must match the hashtable keys exactly (or as an unambiguous prefix, but that's ill-advised), so the _a1 suffix would have to be removed from the keys.
If modifying the input hashtable's keys is not an option, you can use the following command to create a modified copy whose keys have the _a1 suffix removed:
# Create a copy of $args1 in $htArgs with keys without the "_a1" suffix.
$args1.Keys | % { $htArgs = #{} } { $htArgs.($_ -replace '_a1$') = $args1.$_ }

Answer 2

I changed the parameters in the $courses so it will take a hashtable
$courses = {
param($a1)
Write-Host $a1.securitytoken_path_a1 | Format-Table -Property *
C:\Users\fpettigrosso\Desktop\CanvasColleagueIntergration\PowerShells\DownloadInformation.ps1 -securitytoken_path $a1.securitytoken_path_a1 -emailPasswordPath $a1.EmailPasswordPath_a1 -object "courses" -EmailTo $a1.EmailTo_a1 -test $false
}