How to fix Cannot index into a null array in PowerShell - powershell

Question

I'm trying to convert my CSV file to Excel file with some Table format and style but I'm getting "Cannot index into a null array" for some reason. I'll be really appreciated if I can get any help or suggestion. Thanks
function Convert-to-Excel{
$params = #{
AutoSize = $true
TableStyle = 'Medium6'
BoldTopRow = $true
WorksheetName = 'Audit Log'
PassThru = $true
Path = "C:\AuditLogSearch\$((Get-Date).AddDays(-7).ToString('yyyy-MM-dd')) _ $(Get-Date -Format "yyyy-MM-dd") Audit-Log-Records11.xlsx"
}
$modifiedFile = Import-Csv "C:\AuditLogSearch\Modified-Audit-Log-Records.csv"
$actionReference = Import-Csv "C:\AuditLogSearch\Reference\Action.csv"
$xlsx = foreach ($u in $modifiedFile) {
$u.User = (Get-AzureADUser -ObjectId $u.User).DisplayName
New-Object PsObject -Property #{
User = $u.User
"Search Criteria" = $u."Search Criteria"
"Result Status" = $u."Result Status"
"Date & Time" = $u."Date & Time"
"Type of Action" = if (($actionReference | where-object { $_.Name -eq $u."Type of Action" }).Value -ne $null) { ($actionReference | where-object { $_.Name -eq $u."Type of Action" }).Value }
else { $u."Type of Action" }
} | Export-Excel #params
$ws = $xlsx.Workbook.Worksheets[$params.Worksheetname]
$ws.View.ShowGridLines = $false # => This will hide the GridLines on your file
Close-ExcelPackage $xlsx
}
}

Answer 1

You're closing the Excel Package on the first iteration of your loop hence why when it goes to the next it's trying to do something like this:
$null[$null] # => InvalidOperation: Cannot index into a null array
Try modifying your function so it looks like this instead:
First, construct the object[]:
$result = foreach ($u in $modifiedFile) {
$u.User = (Get-AzureADUser -ObjectId $u.User).DisplayName
New-Object PsObject -Property #{
User = $u.User
"Search Criteria" = $u."Search Criteria"
"Result Status" = $u."Result Status"
"Date & Time" = $u."Date & Time"
"Type of Action" = if (($actionReference.........
else { $u."Type of Action" }
}
}
Then export it to Excel:
$xlsx = $result | Export-Excel #params
$ws = $xlsx.Workbook.Worksheets[$params.Worksheetname]
$ws.View.ShowGridLines = $false # => This will hide the GridLines on your file
Close-ExcelPackage $xlsx
One thing to note, PassThru = $true on the $params means that instead of saving the Excel directly we want to save the object on a variable for "further manipulation" and by further manipulation what I mean is, in this case, hiding the GridLines of the worksheet ($ws.View.ShowGridLines = $false) and then closing the package (store it on the disk).
If you don't require to perform any modifications over the worksheet you can just remove the PassThru altogether and do:
$result | Export-Excel #params
Which will close the package and store the Excel on your disk.