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pk.
Asked: 2012-05-25 05:59:40 +0800 CST

OutVariable is broken for Exchange 2010 cmdlets

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It seems that OutVariable is broken when using the Exchange 2010 cmdlets. Is it just my server or is this the case for everyone? I observed the following --

get-mailbox jdoe -OutVariable asdf | out-null
$asdf.getType()

You cannot call a method on a null-valued expression.
At line:1 char:14
+ $asdf.getType <<<< ()
    + CategoryInfo          : InvalidOperation: (getType:String) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull

In the example above, $asdf is never created and get-mailbox jdoe absolutely returns something.

get-childitem -OutVariable asdf | out-null
$asdf.getType()
[PS] C:\temp>$asdf.getType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     ArrayList                                System.Object

In this example, $asdf is created as expected since get-childitem is not an Exchange 2010 cmdlet.

powershell exchange-2010

2 Answers

  1. Best Answer

    To be honest after your previous post I've tried that (my examples where real code I've tested - and it worked in my tests). But I was running them on my EX server (VM). And I haven't used EM Shell, I just added EX snapins to my "regular" powershell.exe

    What's the difference? Well, take a closer look at commands in Exchange Management Shell:

    Get-Command Get-Mailbox | select CommandType

    EMS is using PSRemoting and Implicit remoting under the hood. Why it matters? Well, let's see how -OutVariable will work for impicitly-remoted command that would normally give you results, like ls:

    $Session = New-PSSession -ComputerName EX
Import-PSSession -Prefix Test -Session $Session -CommandName Get-ChildItem
Get-TestChildItem -OutVariable Foo | Out-Null
$Foo -eq $null

True

    You can also take a look at this article for more details on EMS magic: http://www.mikepfeiffer.net/2010/02/managing-exchange-2010-with-remote-powershell/

    ATM I'm not sure if that's a bug, or just side effect of serialization/ deserialization of objects, or just how implicit remoting works in general. But that's definitely root cause, not EX cmdlets themselves (because as you can see - you are not really using cmdlets usually....) So - as I said - you are better of with Add-Member (my example in your linked post had to be updated, previously I've used Get-Mailbox twice instead of Get-MailboxStatistics). It's not bullet proof either (at least my examples where bit fragile) but at least it works... And you can obviously just run "regular" powershell, and just do:

     Add-PSSnappin -Name Microsoft.Exchange.*

    ... and ignore remoting stuff.

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  2. I just encountered the exact same problem with -ErrorVariable: Why are Exchange 2010 cmdlets ignoring ErrorVariable?.

    Whatever the root cause is (implicit remoting is very likely involved), the solution is to use globally-scoped variables:

    Get-Mailbox UserName -OutVariable global:outvar
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