Modifying Variables in Register-ObjectEvent Action Block

Question

I'm connecting to Microsoft Graph for some reports. However, if the report gets close to an hour, I want to automatically re-request a token. I'm able to get the script working in Visual Studio Code, but it doesn't update the token or TimeoutTimer variables in the normal shell. I want to be able to run this as a scheduled task since the run-time is looking at ~8 hours.

I'm assuming this is due to scoping, but I was hoping Global would work, except it's not. I've also tried setting a "state" variable using $job.Module.SessionState.PSVariable.Set() but haven't been able to get that to work (not really familiar, so just coming off some other things I've seen looking around).

    $Global:TimeoutTimer = New-Object timers.timer

    $Global:token = "none"

    $TimerAction = { 
        $Global:tokenRequest = Connect-MicrosoftGraphCustom "Secret Parameters"
        $Global:token = $Global:tokenRequest.access_token
        $Global:TimeoutTimer.Interval = ($Global:tokenRequest.expires_in * 1000) - 100000 
        Write-Host "Inside action: $($Global:TimeoutTimer.Interval)" -ForegroundColor Green
    }

    $job = Register-ObjectEvent -InputObject $Global:TimeoutTimer -EventName Elapsed -Action $TimerAction 
    $Global:TimeoutTimer.Enabled = $true

    sleep -Milliseconds 100

    $i = 0
    while ($i -le 5)
    {
        Write-host "Function Return: $($token)" -ForegroundColor Red
        Write-Host "Global Variable: $($Global:Token)" -ForegroundColor Gray
        Write-Host "Timer Expires in: $($TimeoutTimer.interval) or $($Global:TimeoutTimer.interval)" -ForegroundColor Blue
        sleep 3600
        $i++
    }

    $Global:timeoutTimer.Enabled = $false

I'm hoping to get some "Inside action: x" output and then some copies of the token as the loop processes. What I'm getting in the shell is just a bunch of "None" and "Timer expires in 100 or 100"

What can I do to get the value of token to update in the appropriate scope without reading a file each time I go to access the token variable?

Zergatul · Accepted Answer · 2019-05-20 19:15:53Z

1

Below is an example how you can change variable, even non-global. The idea is to create closure by using GetNewClosure and put token inside another object (in my case it is hashtable):

$timer = New-Object System.Timers.Timer(1000)

$tokenObj = @{}

$sb = {
    $random = New-Object System.Random
    $tokenObj['token'] = $random.Next(100)
}.GetNewClosure()

Register-ObjectEvent -InputObject $timer -EventName 'Elapsed' -Action $sb

$timer.Start()

for ($i = 0; $i -lt 20; $i++)
{
    Write-Host "Token value: $($tokenObj['token'])"
    Start-Sleep -Milliseconds 400
}

answered May 20, 2019 at 19:15

Zergatul

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1 Comment

MosesTeAwesome Over a year ago

Perfect! For others' reference, if you set the event to a variable, $job in my example code, you'll need to use $job.Module.SessionState.PSVariable.Set() to set the local scope copy.

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