Issue with output of Powershell function - function

Question

I'm writing a function and observing some unusual behavior with the output.
This is the code:
Function Get-CompInfo
{
[Cmdletbinding()]
PARAM
(
[Parameter(ValueFromPipeline=$true)]
[Alias('Comp', 'Host')]
[string[]]$computername
)
Begin
{
}
Process
{
if ($computername -eq $Null) {
$computername=$env:computername
$VerboseOut="No computer specified. Running against local computer $computername :"
}
Else {
$VerboseOut="Getting information for computer $computername :"
}
Write-Verbose $VerboseOut
$CompInfo=Get-WmiObject Win32_Computersystem -computername $computername
$OSInfo=Get-WmiObject Win32_OperatingSystem -computername $computername
$Properties = [ordered]#{
'Input'=$computername
'SystemName'=$CompInfo.Name
'Manufacturer'=$CompInfo.Manufacturer
'Model'=$CompInfo.Model
'PhysicalMemory'=$CompInfo.TotalPhysicalMemory
'LogicalProcessors'=$CompInfo.NumberOfLogicalProcessors
'OSCaption'=$OSInfo.Caption
'OSArchitecture'=$OSInfo.OSArchitecture
'ServicePackMajorVersion'=$OSInfo.ServicePackMajorVersion}
# Output Information
$obj=New-Object -TypeName PSobject -Property $Properties
write-output $obj
}
End
{
}
}
When passing parameters from the pipline:
"karuma", "localhost" | Get-CompInfo
Input : {karuma}
SystemName : KARUMA
Manufacturer : Hewlett-Packard
Model : h9-1400a
PhysicalMemory : 17115000832
LogicalProcessors : 8
OSCaption : Microsoft Windows 10 Pro
OSArchitecture : 64-bit
ServicePackMajorVersion : 0
Input : {localhost}
SystemName : KARUMA
Manufacturer : Hewlett-Packard
Model : h9-1400a
PhysicalMemory : 17115000832
LogicalProcessors : 8
OSCaption : Microsoft Windows 10 Pro
OSArchitecture : 64-bit
ServicePackMajorVersion : 0
I get the same kind of output when I pass a text file with a list of computer names.
When specifying multiple host names something different:
Get-CompInfo -computername localhost, karuma
Input : {localhost, karuma}
SystemName : {KARUMA, KARUMA}
Manufacturer : {Hewlett-Packard, Hewlett-Packard}
Model : {h9-1400a, h9-1400a}
PhysicalMemory : {17115000832, 17115000832}
LogicalProcessors : {8, 8}
OSCaption : {Microsoft Windows 10 Pro, Microsoft Windows 10 Pro}
OSArchitecture : {64-bit, 64-bit}
ServicePackMajorVersion : {0, 0}
I'm expecting to see table output when passing multiple values as would by seen by piping to format-table.
Any help on what I need to change to get the output as desired would be appreciated.

Answer 1

It's the way you have your function setup... when using the pipeline the PROCESS block will be run once for each object in the pipeline - the $computername param will only contain a single object at a time in this situation.
When you specify two computers in $computername param, you are changing the way the entire function is running as it contains two objects.
It's easy to fix by wrapping your function in a Foreach like so:
Function Get-CompInfo
{
[Cmdletbinding()]
PARAM
(
[Parameter(ValueFromPipeline=$true)]
[Alias('Comp', 'Host')]
[string[]]$computername
)
Begin {}
Process
{
Foreach ($computer in $computername) {
if ($computer -eq $Null) {
$computer=$env:computername
$VerboseOut="No computer specified. Running against local computer $computer :"
}
Else {
$VerboseOut="Getting information for computer $computer :"
}
Write-Verbose $VerboseOut
$CompInfo=Get-WmiObject Win32_Computersystem -computername $computer
$OSInfo=Get-WmiObject Win32_OperatingSystem -computername $computer
$Properties = [ordered]#{
'Input'=$computer
'SystemName'=$CompInfo.Name
'Manufacturer'=$CompInfo.Manufacturer
'Model'=$CompInfo.Model
'PhysicalMemory'=$CompInfo.TotalPhysicalMemory
'LogicalProcessors'=$CompInfo.NumberOfLogicalProcessors
'OSCaption'=$OSInfo.Caption
'OSArchitecture'=$OSInfo.OSArchitecture
'ServicePackMajorVersion'=$OSInfo.ServicePackMajorVersion}
# Output Information
$obj=New-Object -TypeName PSobject -Property $Properties
write-output $obj
}
}
End {}
}