Logical comparison returning different result for same values

Question

I am absolutely lost as to what is happening here. I am simply comparing the values of two numbers and returning the result. When I'm doing it in a custom property, the result is always False, even though the value is indeed greater. When I take out just the comparison into its own line after the Select-Object operation, the correct result, True, is displayed.

Code examples:

$var = Get-BrokerDesktop -Filter {HostedMachineName -eq $machineName} | 
Select-Object -Property MachineName,
@{L="UptimeHours";E={(New-TimeSpan $_.LastHostingUpdateTime (Get-Date)).TotalHours}}, 
@{L='UptimeFormatted';E={'{0:%d} Days & {0:%h\:mm\:ss}' -f (New-TimeSpan $_.LastHostingUpdateTime (Get-Date))}},
@{L="ToRestart";E={[int]$_.UptimeHours -gt 24}},
RegistrationState     

[int]$var.UptimeHours -gt 24

For the record, UptimeHours is 87 in this case. 87.3 before the integer cast.

I am beyond confused how two identical logical comparisons can return different values.

Answer 1

When using Select-Object with calculate properties, the $_ inside the property expression refers to the current input object - which doesn't have an UptimeHours property, otherwise you wouldn't need to create it in the first place :)

Either repeat the same time span calculation in both expressions:

...,@{L="ToRestart";E={[int](New-TimeSpan $_.LastHostingUpdateTime (Get-Date)).TotalHours -gt 24}},...

... or chain an extra Select-Object command onto the pipeline so you can select the last property based on the value of the ones first introduced with Select-Object:

... |Select-Object -Property MachineName,
    @{L="UptimeHours";E={(New-TimeSpan $_.LastHostingUpdateTime (Get-Date)).TotalHours}}, 
    @{L='UptimeFormatted';E={'{0:%d} Days & {0:%h\:mm\:ss}' -f (New-TimeSpan $_.LastHostingUpdateTime (Get-Date))}},
    RegistrationState | Select-Object -Property *,@{L="ToRestart";E={[int]$_.UptimeHours -gt 24}}