Cannot execute same powershell function twice, gives error - powershell

Question

I'm fairly new to powershell and I'm basically writing a script which performs a join on several .csv files based on a primary column. I am using the Join-Collections script from here: http://poshcode.org/1461
As I need to combine 5 .csv files, I need to run this function 4 times.
On the first run, it works fine, but then trying to run the function again gives 'No object specified to the cmd-let' errors.
In trying to debug, I've literally copy-and-pasted the line and only changed the variable name to make a new variable.
I must be doing something fundamentally wrong...
$SumFile = "VMSummary.csv"
$MemFile = "VMMemory.csv"
$ProcFile = "VMProcessor.csv"
$OSFile = "VMOS.csv"
$NicFile = "VMNics.csv"
$SumFileCSV = Import-Csv $SumFile | Select VMElementName,GuestOS,Heartbeat,MemoryUsage,IpAddress
$MemFileCSV = Import-Csv $MemFile | Select VMElementName,Reservation
$ProcFileCSV = Import-Csv $ProcFile
$OSFileCSV = Import-Csv $OSFile
$NicFileCSV = Import-Csv $NicFile
$JoinColumn = "VMElementName"
function Join-Collections {
PARAM(
$FirstCollection
, [string]$FirstJoinColumn
, $SecondCollection
, [string]$SecondJoinColumn=$FirstJoinColumn
)
PROCESS {
$ErrorActionPreference = "Inquire"
foreach($first in $FirstCollection) {
$SecondCollection | Where{ $_."$SecondJoinColumn" -eq $first."$FirstJoinColumn" } | Join-Object $first
}
}
BEGIN {
function Join-Object {
Param(
[Parameter(Position=0)]
$First
,
[Parameter(ValueFromPipeline=$true)]
$Second
)
BEGIN {
[string[]] $p1 = $First | gm -type Properties | select -expand Name
}
Process {
$Output = $First | Select $p1
foreach($p in $Second | gm -type Properties | Where { $p1 -notcontains $_.Name } | select -expand Name) {
Add-Member -in $Output -type NoteProperty -name $p -value $Second."$p"
}
$Output
}
}
}
}
$Temp = Join-Collections $SumFileCSV $JoinColumn $MemFileCSV $JoinColumn
$Temp
##BREAKS HERE
$Temp2 = Join-Collections $SumFileCSV $JoinColumn $MemFileCSV $JoinColumn
UPDATE
It gives the following error:
No object has been specified to the get-member cmdlet
+ foreach($p) in $Second | gm <<<< -type Properties | Where { $p1 -notcontains $_.Name } | select -expand Name)
The csv data is pretty straight forward. When I print out $Temp just before it breaks, it spits out:
GuestOS : Windows Server (R) 2008 Standard
Heartbeat : OK
IpAddress : 192.168.48.92
MemoryUsage : 1024
VMElementName : VM015
Reservation : 1024
GuestOS : Windows Server (R) 2008 Standard
Heartbeat : OK
IpAddress : 192.168.48.151
MemoryUsage : 1028
VMElementName : VM053
Reservation : 1028
GuestOS : Windows Server (R) 2008 Standard
Heartbeat : OK
IpAddress : 192.168.48.214
MemoryUsage : 3084
VMElementName : VM065
Reservation : 3084
GuestOS :
Heartbeat :
IpAddress :
MemoryUsage :
VMElementName : VM074
Reservation : 1024
GuestOS : Windows Server 2008 R2 Standard
Heartbeat : OK
IpAddress : 192.168.48.32
MemoryUsage : 3072
VMElementName : VM088
Reservation : 3072
GuestOS : Windows Server (R) 2008 Enterprise
Heartbeat : OK
IpAddress : 192.168.48.81
MemoryUsage : 3084
VMElementName : VM090
Reservation : 3084
GuestOS : Windows Server 2008 R2 Enterprise
Heartbeat : OK
IpAddress : 192.168.48.82
MemoryUsage : 5120
VMElementName : VM106
Reservation : 5120
The rest of the .csv data is the same sort of stuff - just stats on different servers.
Ideally what I want to do is this :
$Temp = Join-Collections $SumFileCSV $JoinColumn $MemFileCSV $JoinColumn
$Temp = Join-Collections $Temp $JoinColumn $ProcFileCSV $JoinColumn
$Temp = Join-Collections $Temp $JoinColumn $OSFileCSV $JoinColumn
$Temp = Join-Collections $Temp $JoinColumn $NicFileCSV $JoinColumn | Export-Csv "VMJoined.csv" -NoTypeInformation -UseCulture

Answer 1

This code works fine on Powershell v3 CTP 2 (which is probably what #manojlds is using). In Powershell V2 however the parameter $second of the Join-Object function is not bound when invoking Join-Collections the second time. This can be easily verified by adding the following line to the process block inside the Join-Object function:
$psboundparameters | out-host
You will notice that when invoking Join-Collections for the first time both parameters (of Join-Object are bound, however the second time $second is no longer bound.
It is unclear what is causing this behaviour, but since it seems to be working in Powershell V3 I'm guessing it's a bug.
To make the function work in Powershell V2 one could explicitly bind the parameters by replacing this line:
$SecondCollection | Where{ $_."$SecondJoinColumn" -eq $first."$FirstJoinColumn" } | Join-Object $first
by this line:
$SecondCollection | Where{ $_."$SecondJoinColumn" -eq $first."$FirstJoinColumn" } | %{Join-Object -first $first -second $_}