替换PowerShell输出中的NULL值

Question

I'm really struggling with what seems to be a simple thing. Any help is appreciated...

tldr; i'm trying to find and replace blank or NULL values from powershell output to "No Data"

I am using the following powershell script to obtain installed application information

Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*

Below is sample output of the above script (filtered to my liking). I am taking this data, exporting it to CSV, in order to import into another application for analysis at a later time.

Host             : Computer1
DisplayName      : AutoDWG DWG DXF Converter 2015
Version          : 
Publisher        : 
InstallDate      : 
arrival_datetime : 2015-11-03T09:42:18

Host             : Computer2
DisplayName      : Beyond Compare Version 3.1.11
Version          : 
Publisher        : Scooter Software
InstallDate      : 20150218
arrival_datetime : 2015-11-03T09:42:18

the CSV export puts the data in the correct format, but where items have no data for version, publisher, etc..., it represents it as ",," (see below)

"Computer1","AutoDWG DWG DXF Converter 2015",,,,"2015-11-03T09:54:21"
"Computer2","Beyond Compare Version 3.1.11",,"Scooter Software","20150218","2015-11-03T09:54:21"

When importing the CSV, the blank values are re-interpreted as NULL, which throws the program for a loop, as it is expecting a string. I am attempting to change those to the string "No Data" but am having lots of trouble...

What would be the best way to handle this?

Answer 1

You could inspect the property values as they are piped from the Import-Csv cmdlet, and change them. Example:

Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | 
ForEach-Object { 
foreach ($p in $_.PSObject.Properties) 
{ 
 if ($p.Value -eq [string]::Empty)
 {
  $p.Value = 'No Data'
 }
} 
 Write-Output $_
}

Answer 2

Using Select-Object would be your best bet. Just pipe the data to Select-Object , but customize each desired property as follows:

Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | 
  Select-Object Host, DisplayName, @{
    Label = "Version"
    Expression = { if ($_.Version) { $_.Version } else { "No Data" } }
  }, Other Properties

Answer 3

Building off of this answer , you could generate the calculated properties like this:

$SelectProperties = "Host","DisplayName"
$NoDataFields = "Version","Publisher","InstallDate"

$SelectProperties += $NoDataFields|ForEach-Object {
    @{
      Label = $_
      Expression = [scriptblock]::Create("if(`$_.""$_""){ `$_.""$_"" } else { ""No Data"" }")
    }
}

$Data = Import-Csv -Path "C:\SomePath.csv" | 
  Select-Object $SelectProperties

Answer 4

Do your columns have headers? This was how I did it, when I exported a CSV of groups and their owners. For any group that didn't have an owner in the "ManagedBy" column, it fills the field with "No Owner" instead of a blank space:

$CSVData = Import-Csv $TempCSV -Header "samAccountName", "ManagedBy"  
$CSVData | %{
if($_.ManagedBy -eq "") {$_.ManagedBy="No Owner"}
} 
$CSVData | Export-Csv $Filename -NoTypeInformation

You could just change the "ManagedBy" to your header name and the "$_.ManagedBy" to what you need, then obviously "No Owner" would be "No Data".

Answer 5

Another option that might work:

$TargetFile = "C:\temp\replaceNull.csv"
$File = Get-Content $TargetFile
$Output = @()
foreach ($Line in $File) {
    $Output += $Line -replace ",,",",No Data,"
}
$Output | Set-Content $TargetFile