Change and add data to CSV file

Question

I have a script that should look in a CSV file and modify it. My file looks like this:

"mydata","module1","module2","module3","module4","module5"
"kk-ll","module1","","module3","",""
"kk-pp","module1","","module3","",""  

In case the data in column mydata exists: modify value in column $Module.
In case it does not exist: add a new line to the file.

The code I wrote for the fist part is OK, for the second part (updating the file) it's not working.

$ExistingCSV = Import-Csv MyCsv.csv
if ($ExistingCSV.mydata -eq "$LOT-$WID") {
    $ExistingCSV | ForEach-Object {
        if ($_.mydata -eq "$LOT-$WID") {
            $_.$Module = $Module
        }
    }

    $ExistingCSV | Export-Csv $ProgressLogPath\$LOT.csv -NoTypeInformation
} else {
    $ExistingCSV.mydata = "$LOT-$WID"
    $ExistingCSV.$Module = $Module
    Add-Content $ExistingCSV -Value $_.Lot_WaferID $_.$Module $_.ScriptLogPath

    $ExistingCSV | Export-Csv $ProgressLogPath\$LOT.csv -NoTypeInformation
}

Answer 1

I would use -contains instead of -eq, but since PowerShell operators work as enumerators the latter should work too in your case.

If a match is found, modify the existing data and export the result back to the CSV. Otherwise all you need to do is create a custom object with the data you want to add, and append that to the CSV.

$csv = 'C:\path\to\your.csv'

$ExistingCSV = Import-Csv $csv
if ($ExistingCSV.mydata -contains "$LOT-$WID") {
    foreach ($row in $ExistingCSV) {
        if ($row.mydata -eq "$LOT-$WID") {
            $row.$Module = $Module
        }
    }
    $ExistingCsv | Export-Csv $csv -NoType
} else {
    $obj = New-Object -Type PSObject -Property @{
        'mydata'  = "$LOT-$WID"
        'module1' = $null
        'module2' = $null
        'module3' = $null
        'module4' = $null
        'module5' = $null
    }
    $obj.$Module = $Module
    $obj | Export-Csv $csv -NoType -Append
}

Replace $null with whatever value the moduleX fields are supposed to have.