How to append error from Get-ADComputer to table? - powershell

Question

I am trying to query multiple computers from the Domain using Get-ADComputer. I would like to append the pc name I queryed to the array with the word "error" or a nonsensical date or even a blank value in that spot.
Import-Module ActiveDirectory
$PCNames = "laptop-namea", "laptop-nameb", "laptop-badname"
$Output = #()
$Output = foreach ($PC in $PCNames) {
try {
Get-ADComputer -Identity $PC -Properties * |
Select-Object Name, LastLogonDate
} catch {
$Output += ($PC)
}
}
Current output:
Name LastLogonDate
---- -------------
LAPTOP-NAMEA 1/27/2019 10:37:13 AM
LAPTOP-NAMEB 1/22/2019 8:23:02 AM
Wanted/expected output:
Name LastLogonDate
---- -------------
LAPTOP-NAMEA 1/27/2019 10:37:13 AM
LAPTOP-NAMEB 1/22/2019 8:23:02 AM
LAPTOP-BADNAME

Answer 1

Use -Filter instead of -Identity to avoid throwing errors in case of invalid names.
$Output = foreach ($PC in $PCNames) {
New-Object -Type PSObject -Property #{
'Name' = $PC
'LastLogon' = Get-ADComputer -Filter "Name -eq '$PC'" -Property LastLogonDate |
Select-Object -Expand LastLogonDate
}
}
Beware that querying AD for each individual computer is time-consuming. If the number of queries grows beyond a certain point it's better to query all computers, put them into an appropriate data structure (usually a hashtable), and then look up the desired information in that data structure.
$computers = #{}
Get-ADComputer -Filter '*' -Property LastLogonDate | ForEach-Object {
$computers[$_.Name] = $_.LastLogonDate
}
$Output = foreach ($PC in $PCNames) {
New-Object -Type PSObject -Property #{
'Name' = $PC
'LastLogon' = $computers[$PC].LastLogonDate
}
}

Answer 2

Try - Catch - Finally blocks handle terminating errors. Apply the common parameter -ErrorAction -Stop as follows:
Import-Module ActiveDirectory
$PCNames = "laptop-namea","laptop-nameb","laptop-badname"
$Output = ForEach ($PC in $PCNames)
{
try{
Get-ADComputer -Identity $PC -Properties * -ErrorAction Stop |
Select-Object Name, LastLogonDate
}
catch{
[PSCustomObject]#{Name=$PC;LastLogonDate=$null}
}
}