Ignoring Null Values - powershell

Question

I have a question regarding Null values.
The script below works fine, but will return errors when nothing is in my Z (optical drive). Obviously if nothing is in the optical drive it is basically null, but I have not found a way around that as of yet. I know it's probably a simple fix and am hoping someone here can help.
Function GetDisk
{
Param(
$ComputerName = $env:COMPUTERNAME,
[Switch]$PassThru
)
# ...
}
Function Get-ColorSplat
{
# Create color Splats
$C1 = #{ForegroundColor="Green"}
$C2 = #{ForegroundColor="Yellow"}
$C3 = #{ForegroundColor="Red"}
# Create color constants in the previous scope.
New-Variable -Name "Good" -Value $C1 -Scope 1
New-Variable -Name "Problem" -Value $C2 -Scope 1
New-Variable -Name "Bad" -Value $C3 -Scope 1
} # End: Get-ColorSplat
Function Write-ColorOutput
{
Param($DiskInfo)
Write-Host""
Write-Host -NoNewLine "OS Version: "
Get-CimInstance Win32_OperatingSystem | Select-Object Caption | ForEach{ $_.Caption }
Write-Host""
# Display the headers.
Write-host "SystemName DeviceID VolumeName Size(GB) FreeSpace(GB) %FreeSpace(GB) Date"
Write-host "---------- -------- ----------- -------- ------------ -------------- ----------------"
# Display the data.
ForEach ($D in $DiskInfo)
{
$PSComputerName = $D.PSComputerName.PadRight(6)
$DeviceID = $D.DeviceID.ToString().PadRight(6).Remove(5)
$VolumeName = $D.VolumeName.ToString().PadRight(20).Remove(19)
$SizeGB = $D.SizeGB.ToString().PadRight(6).Remove(5)
$FSGB = $D.FreeSpaceGB.ToString().PadRight(6).Remove(5)
$PFS = $D.PercentFS.ToString().PadRight(7).Remove(6)
$Date = $D.Date.ToString().PadRight(20).Remove(19)
If ($D.PercentFS -ge 50)
{ Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" #Good }
ElseIf (($D.PercentFS -lt 50) -and ($D.PercentFS -GE 40))
{ Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" #Problem }
Else
{ Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" #Bad }
}
}
# Get the color splats
Get-ColorSplat
$DiskInfo = Get-WMIObject win32_logicalDisk -ComputerName $env:computername | Select-Object PSComputerName, DeviceID, Size, VolumeName,
#{name="SizeGB"; expression={"{0:N2}" -f ($_.Size/1gb)}},
#{Name="FreeSpaceGB"; expression={"{0:N2}" -f ($_.FreeSpace/1gb)}},
#{Name="PercentFS"; expression={"{0:N2}%" -f(($_.FreeSpace/$_.size)*100)}},
#{name="Date"; expression={$(Get-Date -Format "g")}}
#$ErrorActionPreference= 'silentlycontinue'
If (!$PassThru) {
Write-ColorOutput -DiskInfo $DiskInfo
}
Else {
Write-Output $DiskInfo
}
}

Answer 1

You had to problems several values of $D were returning $null but you aren't checking their value (e.g. $D.VolumeName).
The second problem is that you are creating the global variables multiple times (e.g. New-Variable -Name "Good").
I suggest you refactor so that variable creation is in "Get-ColorSplat" if you are going to call it several times.
Edit #1 fixed padding in output table
Function GetDisk
{
Param(
$ComputerName = $env:COMPUTERNAME,
[Switch]$PassThru
)
# ...
}
Function Get-ColorSplat
{
# Create color Splats
$C1 = #{ForegroundColor="Green"}
$C2 = #{ForegroundColor="Yellow"}
$C3 = #{ForegroundColor="Red"}
# Create color constants in the previous scope.
if(Get-Variable Good -Scope Global -ErrorAction SilentlyContinue){}
else{New-Variable -Name "Good" -Value $C1 -Scope 1}
if(Get-Variable Problem -Scope Global -ErrorAction SilentlyContinue){}
else{New-Variable -Name "Problem" -Value $C2 -Scope 1}
if(Get-Variable Bad -Scope Global -ErrorAction SilentlyContinue){}
else{New-Variable -Name "Bad" -Value $C3 -Scope 1}
} # End: Get-ColorSplat
Function Write-ColorOutput
{
Param($DiskInfo)
Write-Host""
Write-Host -NoNewLine "OS Version: "
Get-CimInstance Win32_OperatingSystem | Select-Object Caption | ForEach{ $_.Caption }
Write-Host""
# Display the headers.
Write-host "SystemName DeviceID VolumeName Size(GB) FreeSpace(GB) %FreeSpace(GB) Date"
Write-host "---------- -------- ----------- -------- ------------ -------------- ----------------"
# Display the data.
ForEach ($D in $DiskInfo)
{
$PSComputerName = $D.PSComputerName.PadRight(6)
$DeviceID = $D.DeviceID.ToString().PadRight(6).Remove(5)
$Dname = $D.VolumeName
if($Dname){$VolumeName = $D.VolumeName.ToString().PadRight(20).Remove(19)}
else{$VolumeName = ' '}
$SizeGB = $D.SizeGB.ToString().PadRight(6).Remove(5)
$FSGB = $D.FreeSpaceGB.ToString().PadRight(6).Remove(5)
$PercentFS = $D.PercentFS
if($PercentFS){$PFS = $D.PercentFS.ToString().PadRight(7).Remove(6)}
else{$PFS = ' '}
$Date = $D.Date.ToString().PadRight(20).Remove(19)
If ($D.PercentFS -ge 50)
{ Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" #Good }
ElseIf (($D.PercentFS -lt 50) -and ($D.PercentFS -GE 40))
{ Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" #Problem }
Else
{ Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" #Bad }
}
}
# Get the color splats
Get-ColorSplat
$DiskInfo = Get-WMIObject win32_logicalDisk -ComputerName $env:computername | Select-Object PSComputerName, DeviceID, Size, VolumeName,
#{name="SizeGB"; expression={"{0:N2}" -f ($_.Size/1gb)}},
#{Name="FreeSpaceGB"; expression={"{0:N2}" -f ($_.FreeSpace/1gb)}},
#{Name="PercentFS"; expression={"{0:N2}%" -f(($_.FreeSpace/$_.size)*100)}},
#{name="Date"; expression={$(Get-Date -Format "g")}}
#$ErrorActionPreference= 'silentlycontinue'
If (!$PassThru) {Write-ColorOutput -DiskInfo $DiskInfo}
Else {Write-Output $DiskInfo}

Answer 2

Got it figured out - thanks to all that commented and helped me.
Function GetDisk
{
Param(
$ComputerName = $env:COMPUTERNAME,
[Switch]$PassThru
)
Function Write-ColorOutput
{
Param($DiskInfo)
Write-Host""
Write-Host -NoNewLine "OS Version: "
Get-CimInstance Win32_OperatingSystem | Select-Object Caption | ForEach{ $_.Caption }
Get-CimInstance Win32_OperatingSystem | Select-Object CSName, InstallDate, BuildNumber, OSArchitecture, BootDevice | Format-Table -AutoSize | Out-String | Write-Host -ForegroundColor Green
Get-PhysicalDisk | Select-Object $env:computername, FriendlyName, SerialNumber, MediaType, OperationalStatus, HealthStatus | Format-Table -AutoSize | Out-String | Write-Host -ForegroundColor Green
Write-Host""
# Display the headers.
Write-host "SystemName DeviceID VolumeName Size(GB) FreeSpace(GB) %FreeSpace(GB) Date"
Write-host "---------- -------- ----------- -------- ------------ -------------- ----------------"
# Display the data.
ForEach ($D in $DiskInfo)
{
$PSComputerName = $D.PSComputerName.PadRight(6)
$DeviceID = $D.DeviceID.ToString().PadRight(6).Remove(5)
$Dname = $D.VolumeName
if($Dname){$VolumeName = $D.VolumeName.ToString().PadRight(20).Remove(19)} else{$VolumeName = ' '}
$SizeGB = $D.SizeGB.ToString().PadRight(6).Remove(5)
$FSGB = $D.FreeSpaceGB.ToString().PadRight(6).Remove(5)
$PercentFS = $D.PercentFS
if($PercentFS){$PFS = $D.PercentFS.ToString().PadRight(7).Remove(6)} else{$PFS = ' '}
$Date = $D.Date.ToString().PadRight(20).Remove(19)
If ($D.PercentFS -ge 50)
{Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" -ForegroundColor Green}
ElseIf (($D.PercentFS -lt 50) -and ($D.PercentFS -GE 40))
{Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" -ForegroundColor Yellow}
Else
{Write-Host "$PSComputerName $($DeviceID) $($VolumeName)$($SizeGB) $($FSGB) $($PFS) $($Date)" -ForegroundColor Red}
}
Get-PhysicalDisk | Get-StorageReliabilityCounter | Select-Object $env:computername, PowerOnHours, Temperature, Wear, ReadErrorsTotal, WriteErrorsTotal, FlushLatencyMax, WriteLatencyMax | Format-Table -AutoSize | Out-String | Write-Host -ForegroundColor Green
Disk | Select-Object | Format-Table -AutoSize | Out-String | Write-Host -ForegroundColor Green
}
$DiskInfo = Get-WMIObject win32_logicalDisk -ComputerName $env:computername | Select-Object PSComputerName, DeviceID, Size, VolumeName,
#{name="SizeGB"; expression={"{0:N2}" -f ($_.Size/1gb)}},
#{Name="FreeSpaceGB"; expression={"{0:N2}" -f ($_.FreeSpace/1gb)}},
#{Name="PercentFS"; expression={"{0:N2}%" -f(($_.FreeSpace/$_.size)*100)}},
#{name="Date"; expression={$(Get-Date -Format "g")}}
#$ErrorActionPreference= 'silentlycontinue'
If (!$PassThru) {Write-ColorOutput -DiskInfo $DiskInfo} Else {Write-Output $DiskInfo}
Write-Host""
Write-Host""
}