Add column and assign value to an existing array

Question

I want to add a column and a value to an existing array generated from a CSV.

This is my code:

$mycsv = "C:\Users\test\Documents\serveurs.csv"
$servers = Import-Csv $mycsv

This is the result:

ServerName                              Ip
----------                              --
Castor                                  172.22.0.64
Pollux                                  172.22.0.67

I want to add new column with value for each ServerName, like this:

ServerName                              Ip                  Available
----------                              --                  ---------
Castor                                  172.22.0.64         Yes
Pollux                                  172.22.0.67         No

I tried the code below:

$item = New-Object PSObject
$item | Add-Member -Type NoteProperty -Name 'Available' -Value 'Yes'

$servers += $item

But it's actually not working, can anyone help me?

The final idea is to have value assigned if the server is reachable or not over the network, using Test-Connection cmdlet.

Answer 1

You could use a calculated property for determining the availability of each server:

$csv1 = 'C:\Users\test\Documents\serveurs.csv'
$csv2 = 'C:\Users\test\Documents\serveurs2.csv'

Import-Csv $csv1 |
    Select-Object ServerName, Ip,
        @{n='Available';e={[bool](Test-Connection -Count 1 $_.Ip 2>$null)}} |
    Export-Csv $csv2 -NoType

Note, however, that even when limiting the test to a single probe per server this may take some time, since all items are processed sequentially. If you have a lot of servers to test, you may want to run the checks as parallel jobs:

$csv = 'C:\Users\test\Documents\serveurs.csv'

$servers = Import-Csv $csv

# clear job queue
Remove-Job *
# load job queue with test jobs
$servers | ForEach-Object {
    Start-Job -ScriptBlock {
        $args[0]
        [bool](Test-Connection -Count 1 $args[0] 2>$null)
    } -ArgumentList $_.Ip
}
# wait for jobs to finish
do {
    Start-Sleep -Milliseconds 100
} while (Get-Job -State 'Running')

# gather job results into hashtable
$availability = @{}
Get-Job | ForEach-Object {
    $result = Receive-Job -Id $_.Id
    $availability[$result[0]] = $result[1]
    Remove-Job -Id $_.Id
}

# add availability column to server data and export back to CSV
$servers |
    Select-Object ServerName, Ip, @{n='Available';e={$availability[$_.Ip]}} |
    Export-Csv $csv -NoType

Answer 2

Populating the field value aside, another option for getting the property added is to use Select-Object.

$csv = 'C:\Users\test\Documents\serveurs.csv'
$servers = Import-Csv $csv | select *,Availability

Then populate availability however you choose.

If you're going to use background jobs to multithread I think you'd be better off breaking the server names up into groups and setting a background job to work on each group. It takes about 5 seconds to set up and tear down a background job, and using them for trivial tasks like pinging a single computer can be counter-productive.

It's more work to code, but if you want to multi-thread that I think a runspace pool would produce results much faster than background jobs in this application.