Method failed 'op_Addition'

Hey all,

I think I've somehow managed to hose smthng but I have no idea what.
I've got a relatively simple script that worked until this morning.
Here's the offending command I'm running within a for-next loop (all one
line):

$ResultCont += ( Get-wmiobject -class exchange_SMTPQueue -Namespace
ROOT\MicrosoftExchangev2 -ComputerName $objItem | Select-Object
VirtualMachine,LinkName,QueueName,MessageCount,Size | Where-Object
-FilterScript {$_.MessageCount -ne 0} )

Here's the error it now generates AFTER the first iteration of the loop:

Method invocation failed because [System.Management.Automation.PSObject]
doesn't contain a method named 'op_Addition'.
At C:\Scripts\ExchQueues.ps1:5 char:16
+ $ResultCont += <<<< ( Get-wmiobject -class exchange_SMTPQueue
-Namespace ROOT\MicrosoftExchangev2 -ComputerName
$objItem | Select-Object
VirtualMachine,LinkName,QueueName,MessageCount,Size | Where-Object
-FilterScript {$_.MessageCo
unt -ne 0} )

It looks to me like PS how now decided that it doesn't like it's own +=
operator. Any ideas what I did to cause this or how I'd go about
restoring it again?

--Jonathan "smthng" Kalmes
http://smthng.info

"Jonathan Kalmes" <smthng@smthng.info> wrote in message
news:%23t84Y9xOHHA.3544@TK2MSFTNGP03.phx.gbl...
> Hey all,
>
> I think I've somehow managed to hose smthng but I have no idea what. I've
> got a relatively simple script that worked until this morning. Here's the
> offending command I'm running within a for-next loop (all one line):
>
> $ResultCont += ( Get-wmiobject -class exchange_SMTPQueue -Namespace
> ROOT\MicrosoftExchangev2 -ComputerName $objItem | Select-Object
> VirtualMachine,LinkName,QueueName,MessageCount,Size |
> Where-Object -FilterScript {$_.MessageCount -ne 0} )
>
> Here's the error it now generates AFTER the first iteration of the loop:
>
> Method invocation failed because [System.Management.Automation.PSObject]
> doesn't contain a method named 'op_Addition'.
> At C:\Scripts\ExchQueues.ps1:5 char:16
> + $ResultCont += <<<< ( Get-wmiobject -class
> exchange_SMTPQueue -Namespace ROOT\MicrosoftExchangev2 -ComputerName
> $objItem | Select-Object
> VirtualMachine,LinkName,QueueName,MessageCount,Size |
> Where-Object -FilterScript {$_.MessageCo
> unt -ne 0} )
>
> It looks to me like PS how now decided that it doesn't like it's own +=
> operator. Any ideas what I did to cause this or how I'd go about
> restoring it again?

I would guess that you previously assigned an object of type PSObject to the
variable $ResultCont. Try executing this first before your command above:

$ResultCont = @()

The addition operation it attempts is going to be based on the type of of
variable on the left. In this case, since += is the equivalent of:

$ResultCont = $ResultCont + (....)

It is the type of $ResultCont that dictates the behavior of the + operator.
Not sure how the algorithm works if $ResultCont is non-existant or null but
it seems to use the "type" of the right hand operand in that case.

--
Keith

Keith Hill [MVP] wrote:
<snip>
> I would guess that you previously assigned an object of type PSObject to the
> variable $ResultCont. Try executing this first before your command above:
>
> $ResultCont = @()

Sweet! You da man! BTW... I hadn't declared or assigned $ResultCont at
all. I assumed it would always be null when starting, which in my case
is true enough that it doesn't really matter. But...

My problem was that the WMI query can return multiple queues on the
first iteration of the loop. If that happens, there are no problems as
the first assignment includes multiple values, so it's automagically
created as an array. The reason it failed today is because I'd cleaned
up our queues and only ONE was found to have messages on the first
iteration. That would cause $ResultCont to be assigned as a simple
string, not an array. Hence, all the other assignments would fail.
Oops. In short, I needed to assign it as an empty array and not
assume it would always receive a multi-valued assignment on the first
iteration of the loop.

Thanks again!

--Jonathan "smthng" Kalmes
http://smthng.info