What is the reason for Powershell Excel SaveAs / Exception null-valued expression? - excel

Question

I'm working on a PowerShell script which unzips some .csv files, writes the contents inside an existing .xlsx file and saves this as a new .xlsx.
After some calculation I start a batch file from my PL/SQL code with DBMS.SCHEDULE. After the .bat file did some preparation it starts the PowerShell script.
I'm getting no error if I run the .bat file manually in a Windows command prompt window.
But I get an error while saving the .xlsx file if it is started from PL/SQL.
System.Management.Automation.RuntimeException You cannot call a method on a null-valued expression.
I tried to search in world wide web for a solution on this error but couldn't find one.
This is the line which produces the error message:
$WB.SaveAs($fileName, 51, [Type]::Missing, [Type]::Missing, $false, $false, 1, 2) | Out-Null
Here is the whole code:
#Unzip Files
function Unzip($file, $destination){
Expand-Archive $file -Destination $destination -Force
if (Test-Path $file) {
Remove-Item $file
}
}
#Add file to existing zip
function addZip($file, $destination){
Compress-Archive -Path $file -Update -DestinationPath $destination
}
#Write CSV into XLSX
function WriteFile($row, $column, $range){
foreach ($content in Get-Content $f.FullName) { #Get row
#If value not empty
if ($content) {
#Set value to cell
$WS.Cells.Item($row, $column) = $content
$colA = $ws.Range("$range$row")
$colrange = $ws.Range("$range$row")
#Split value by delimiter
#https://learn.microsoft.com/en-us/office/vba/api/excel.range.texttocolumns
$colA.TextToColumns($colrange, 1, -4142, $false, $false, $false, $false, $false, $true, "|") | Out-Null
$row = $row + 1
}
}
}
#Start
$XL = New-Object -ComObject Excel.Application
#Disable alerts
$XL.EnableEvents = $false
$XL.DisplayAlerts = $false
$XL.ScreenUpdating = $false
$param = $args[0].SubString(0, $args[0].IndexOf(".")) #Get name
$currentPath = Get-Location
$newPath = "$currentPath\$param\" #Temp new folder
#Create temp folder if exists
if (!(Test-Path $newPath)) {
New-Item -ItemType Directory -Force -Path $newPath
}
#Unzip
Unzip "$currentPath\$param.zip" $newPath
$files = Get-ChildItem -Path $newPath -Recurse #Get files
$XL.Workbooks.Open("$currentPath\test.xlsx")
$WB = $xl.ActiveWorkbook
$fileName = "$newPath"+"test_$param.xlsx"
#Loop through files
foreach ($f in $files) {
if ($f.Basename.ToUpper() -like "*A") {
$WS = $WB.Sheets.Item("A")
$WS.Activate() | Out-Null
WriteFile 10 1 "A" #Row / Column
addZip $f.FullName "$currentPath\$param.zip"
} elseif ($f.Basename.ToUpper() -like "*B") {
$WS = $WB.Sheets.Item("B")
$WS.Activate() | Out-Null
WriteFile 11 1 "A" #Row / Column
addZip $f.FullName "$currentPath\$param.zip"
} elseif ($f.Basename.ToUpper() -like "*C") {
$WS = $WB.Sheets.Item("C")
$WS.Activate() | Out-Null
WriteFile 12 1 "A" #Row / Column
addZip $f.FullName "$currentPath\$param.zip"
}
}
try {
#Delete File if exists
if ((Test-Path $fileName)) {
Remove-Item -Path $fileName -Recurse -Force -Confirm:$false
}
#Save
$WB.SaveAs($fileName, 51, [Type]::Missing, [Type]::Missing, $false, $false, 1, 2) | Out-Null
} catch {
New-Item "$currentPath\log.txt" -ItemType file
$_.Exception.GetType().FullName, $_.Exception.Message, $_.InvocationInfo.ScriptLineNumber |
Out-File "$currentPath\log.txt"
} finally {
#Close, Quit
$WB.Close($false) | Out-Null
$XL.Workbooks.Close()
$XL.Quit() | Out-Null
}
try {
addZip $fileName "$currentPath\$param.zip"
} catch {
New-Item "$currentPath\log1.txt" -ItemType file
$_.Exception.GetType().FullName, $_.Exception.Message, $_.InvocationInfo.ScriptLineNumber |
Out-File "$currentPath\log1.txt"
}
#Delete folder
if ((Test-Path $newPath)) {
Remove-Item -Path $newPath -Recurse -Force -Confirm:$false | Out-Null
}
#Release ComObject
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($XL)
spps -n Excel
This is the .bat file which runs the Powershell script:
powershell.exe -ExecutionPolicy RemoteSigned -File C:\Scripts\write_to_excel.ps1 %1
This is the PL/SQL code which runs the .bat file:
BEGIN
DBMS_SCHEDULER.create_job ('SCHEDULE_POWERSHELL',
job_action => 'c:\windows\system32\cmd.exe',
number_of_arguments => 4,
job_type => 'executable',
enabled => FALSE);
DBMS_SCHEDULER.set_job_argument_value ('SCHEDULE_POWERSHELL', 1, '/q');
DBMS_SCHEDULER.set_job_argument_value ('SCHEDULE_POWERSHELL', 2, '/c');
DBMS_SCHEDULER.set_job_argument_value ('SCHEDULE_POWERSHELL', 3, 'c:\Scripts\run_powershell.bat');
DBMS_SCHEDULER.set_job_argument_value ('SCHEDULE_POWERSHELL', 4, 'test_files.zip');
DBMS_SCHEDULER.enable ('SCHEDULE_POWERSHELL');
DBMS_SCHEDULER.run_job (job_name => 'SCHEDULE_POWERSHELL', use_current_session => TRUE);
EXCEPTION
WHEN OTHERS
THEN
log_trace_message ('SCHEDULE_POWERSHELL: ' || SQLERRM);
log_trace_message ('SCHEDULE_POWERSHELL: ' || DBMS_UTILITY.format_error_backtrace);
END;