Unable to use best practices library for PowerShell - Request object is empty

I'm trying to use the best practices library for PowerShell, but I keep getting this error:

You cannot call a method on a null-valued expression.

For some reason the $request is always empty when I try to use any of the functions in the library.

Here's an example of the code I'm using:

function onInit($context) {
    $context.UseLibraryScript('Script Modules/Library/One-Identity-Libary')
}

function onPreModify($Request) {
    if ($Request.Class -ne "user") { return }

    $tieredAttributes = @(
        'edsvaTier1Required'
        'edsvaTier2Required'
        'edsvaTier3Required'
    )
    if (AreAttributesModified($tieredAttributes, $Request)) {
        #do stuff with attributes
    }
}

I also tried adding $Request | Get-Member | Out-File C:\Request.txt to the functions in library, this generates an empty file.

Am I missing something obvious?

0 Shawn.Ferrier over 2 years ago

Hello, jody.

First, it's been a while, but I don't believe you need to have the "Script Modules" part of the path specified. Just the "Library/One-Identity-Library" portion.

Second, your statement on line 13 calls AreAttributesModified. Don't know the contents of your library, of course, but unless you've changed something, then the "best practice" code uses the function name IsAttributeModified - note the word "attribute" is singlular/no "s".

Lastly, the idea of using onInit at all has, more recently, fallen out-of-favour due to the performance implications it imposes on the Web interface. You might consider using something like Invoke-Command and/or Invoke-Expression instead. That is discussed herein in this thread.

Cheers!
Shawn
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0 jody gilbert over 2 years ago in reply to Shawn.Ferrier

thanks for the tip on Invoke-Expression, I've switched to using that.

the issue appears to be positional parameters, if I name the parameters I can use the functions from the library.
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0 Shawn.Ferrier over 2 years ago in reply to jody gilbert
Agreed... as far as I'm aware, there is no "easy" way to deal with passing named parameters to a PowerShell scriptblock. Here are a couple of useful articles that I came across:

https://stackoverflow.com/questions/27794898/powershell-pass-named-parameters-to-argumentlist

https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_remote_variables

https://stackoverflow.com/questions/4225748/how-do-i-pass-named-parameters-with-invoke-command

Looks to me that the method that would leave you with the most readable code would be to modify the functions in the library to specify positional properties, as discussed in that last StackOverflow link. E.g., something like this:

param( [Parameter(Position=0)] $one , [Parameter(Position=1)] $two )
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