CODEWITHSUNDEEP
powershell
Matt
Matt

Reputation: 1063

having trouble piping values into powershell function

I'm trying to pass the results of an LDAP query (computers) into my Powershell function. However, the function only processes one value. Here's some example code:

Function Get-ComputerName {
    Param(
        [Alias('Computer','ComputerName','HostName')]
        [Parameter(
            Mandatory=$true,
            Position=0,
            ValueFromPipeline=$true
        )]
        [Object[]]$computers
    )
    if(-not($computers)) { Throw “You must supply at least one computer” }

    foreach($computer in $computers) {
        write-host $computer.Name
    }
}

When I run:

Get-ADComputer -SearchBase 'OU="Devices",dc=FVWM1,dc=Local' -Filter '*' | Get-ComputerName

The result is only one computer name printed but there should definitely be more than one. Help! Thanks.

Upvotes: 0

Views: 30

Answers (1)

Chris N
Chris N

Reputation: 7499

When using the pipeline to pass multiple objects into a function, make sure to use the Begin, Process, and End blocks. After building a $computers object of my own, I can replicate the issue.

$computers = @()
$computers += New-Object -TypeName PSObject -Property @{
    Name = "Test"
    Note = "TestTest"
}
$computers += New-Object -TypeName PSObject -Property @{
    Name = "Test2"
    Note = "TestTest"
}
$computers += New-Object -TypeName PSObject -Property @{
    Name = "Test3"
    Note = "TestTest"
}
$computers | Get-InstalledSoftware

This yields test3

The solution is to simply wrap the internals of the function with Process {} like so:

Function Get-InstalledSoftware {
    Param(
        [Alias('Computer','ComputerName','HostName')]
        [Parameter(
            Mandatory=$true,
            Position=0,
            ValueFromPipeline=$true
        )]
        [Object[]]$computers
    )
    Process {
        if(-not($computers)) { Throw “You must supply at least one computer” }

        foreach($computer in $computers) {
            write-host $computer.Name
        }
    }
}

Upvotes: 2

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